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Sample records for phosphoric acid potassium

  1. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this section...

  2. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this section...

  3. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this section...

  4. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this section...

  5. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this section...

  6. Phosphoric acid

    Integrated Risk Information System (IRIS)

    Phosphoric acid ; CASRN 7664 - 38 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  7. Analytical applications of condensed phosphoric acid-III Iodometric determination of sulphur after reduction of sulphate with sodium hypophosphite and either tin metal or potassium iodide in condensed phosphoric acid.

    PubMed

    Mizoguchi, T; Iwahori, H; Ishii, H

    1980-06-01

    Novel methods for the reduction of sulphate to hydrogen sulphide with hypophosphite-tin metal or hypophosphite-iodide in condensed phosphoric acid (CPA) are proposed. The reduction of sulphate with hypophosphite alone does not proceed quantitatively. Sulphate, however, is quantitatively decomposed with hypophosphite when tin metal or potassium iodide is used together with it. The determination of sulphur by the hypophosphite-tin metal-CPA and tin(II)-CPA methods is interfered with by copper on account of the stabilization of copper(I) sulphide, but this interference can be eliminated by adding iodide, e.g. potassium and lead salts. Alum and barytes are quantitatively decomposed within 15 min at 140 and 280 degrees , respectively. The hydrogen sulphide evolved is absorbed in zinc acetate solution at pH 4.5 and then determined by iodometry.

  8. 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).

    PubMed

    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.

  9. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

    Sopchak, David A [Livermore, CA; Morse, Jeffrey D [Martinez, CA; Upadhye, Ravindra S [Pleasanton, CA; Kotovsky, Jack [Oakland, CA; Graff, Robert T [Modesto, CA

    2010-08-17

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  10. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

    Sopchak, David A.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Kotovsky, Jack; Graff, Robert T.

    2010-12-21

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  11. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is...

  12. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 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...

  13. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is...

  14. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 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...

  15. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is...

  16. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 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...

  17. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Phosphoric acid. 182.1073 Section 182.1073 Food... GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is generally recognized as safe when used in...

  18. 21 CFR 182.1073 - Phosphoric acid.

    Code of Federal Regulations, 2010 CFR

    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...

  19. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2010 CFR

    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...

  20. 21 CFR 582.1073 - Phosphoric acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 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...

  1. Acid-permanganate oxidation of potassium tetraphenylboron

    SciTech Connect

    Smith, J.R.

    1993-02-01

    Scoping experiments have been performed which show that potassium tetraphenylboron (KTPB) is rapidly oxidized by permanganate in acidic solutions at room temperature. The main Products are CO[sub 2], highly oxidized organic compounds related to tartaric and tartronic acids, boric acid, and potassium phosphate (when phosphoric acid is used as the source of acid). One liter of 0.6M NaMnO[sub 4]/2.5M H[sub 3]PO[sub 4] solution will destroy up to 8 grams of KTPB. The residual benzene concentration has been measured to be less than the RCRA limit of 0.5 ppm. Approximately 30% of the organic material is released as CO[sub 2] (trace CO) and 0.16% as benzene vapor. The reaction is well behaved, no foaming or spattering. Tests were performed from .15M to near 1M permanganate. The phosphoric acid concentration was maintained at a concentration at least three times that of the permanganate since an excess of acid was desired and this is the ratio that these two reagents are consumed in the oxidation.

  2. Acid-permanganate oxidation of potassium tetraphenylboron

    SciTech Connect

    Smith, J.R.

    1993-02-01

    Scoping experiments have been performed which show that potassium tetraphenylboron (KTPB) is rapidly oxidized by permanganate in acidic solutions at room temperature. The main Products are CO{sub 2}, highly oxidized organic compounds related to tartaric and tartronic acids, boric acid, and potassium phosphate (when phosphoric acid is used as the source of acid). One liter of 0.6M NaMnO{sub 4}/2.5M H{sub 3}PO{sub 4} solution will destroy up to 8 grams of KTPB. The residual benzene concentration has been measured to be less than the RCRA limit of 0.5 ppm. Approximately 30% of the organic material is released as CO{sub 2} (trace CO) and 0.16% as benzene vapor. The reaction is well behaved, no foaming or spattering. Tests were performed from .15M to near 1M permanganate. The phosphoric acid concentration was maintained at a concentration at least three times that of the permanganate since an excess of acid was desired and this is the ratio that these two reagents are consumed in the oxidation.

  3. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 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...

  4. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 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...

  5. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2010 CFR

    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...

  6. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 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...

  7. 46 CFR 151.50-23 - Phosphoric acid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 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...

  8. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-522); or (c) Made of a stainless steel that resists corrosion...

  9. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-522); or (c) Made of a stainless steel that resists corrosion...

  10. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-ENG); or (c) Made of a stainless steel that resists corrosion...

  11. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Special requirements for phosphoric acid. 153.558... Equipment Special Requirements § 153.558 Special requirements for phosphoric acid. A phosphoric acid... phosphoric acid tanks by the Commandant (CG-ENG); or (c) Made of a stainless steel that resists corrosion...

  12. Stabilizing platinum in phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Remick, R. J.

    1982-01-01

    Platinum sintering on phosphoric acid fuel cell cathodes is discussed. The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst dispersed on a conductive carbon support to minimize both cathode polarization and fabrication costs. During operation, however, the active surface area of these electrodes decreases, which in turn leads to decreased cell performance. This loss of active surface area is a major factor in the degradation of fuel cell performance over time.

  13. Stabilizing platinum in phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Remick, R. J.

    1981-10-01

    A carbon substrate for use in fabricating phosphoric acid fuel cell cathodes was modified by catalytic oxidation to stabilize the platinum catalyst by retarding the sintering of small platinum crystallites. Results of 100-hour operational tests confirmed that the rate of platinum surface area loss observed on catalytically oxidized supports was less than that observed with unmodified supports of the same starting material. Fuel cell electrodes fabricated from Vulcan XC-72R, which was modified by catalytic in a nitric oxide atmosphere, produced low platium sintering rates and high activity for the reduction of oxygen in the phosphoric acid environment.

  14. Corrosion free phosphoric acid fuel cell

    DOEpatents

    Wright, Maynard K.

    1990-01-01

    A phosphoric acid fuel cell with an electrolyte fuel system which supplies electrolyte via a wick disposed adjacent a cathode to an absorbent matrix which transports the electrolyte to portions of the cathode and an anode which overlaps the cathode on all sides to prevent corrosion within the cell.

  15. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

  16. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

  17. 40 CFR 721.10431 - Phosphoric acid esters (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid esters (generic). 721... Substances § 721.10431 Phosphoric acid esters (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as phosphoric acid esters (PMNs P...

  18. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2010 CFR

    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...

  19. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

  20. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 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...

  1. 40 CFR 721.10685 - Phosphoric acid, mixed esters (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, mixed esters (generic... Specific Chemical Substances § 721.10685 Phosphoric acid, mixed esters (generic). (a) Chemical substance... phosphoric acid, mixed esters (PMN P-13-170) is subject to reporting under this section for the significant...

  2. 40 CFR 721.10431 - Phosphoric acid esters (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid esters (generic). 721... Substances § 721.10431 Phosphoric acid esters (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as phosphoric acid esters (PMNs P...

  3. Phosphoric Acid Fuel Cell Technology Status

    NASA Technical Reports Server (NTRS)

    Simons, S. N.; King, R. B.; Prokopius, P. R.

    1981-01-01

    A review of the current phosphoric acid fuel cell system technology development efforts is presented both for multimegawatt systems for electric utility applications and for multikilowatt systems for on-site integrated energy system applications. Improving fuel cell performance, reducing cost, and increasing durability are the technology drivers at this time. Electrodes, matrices, intercell cooling, bipolar/separator plates, electrolyte management, and fuel selection are discussed.

  4. Uranium recovery from wet process phosphoric acid

    SciTech Connect

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

    1981-03-24

    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.

  5. Sorption of Phosphoric Acid by Anion-Exchange Membrane

    NASA Astrophysics Data System (ADS)

    Takahashi, Hiroshi; Kikuchi, Ken-Ichi

    Sorption equilibrium of phosphoric acid by strongly basic anion-exchange membrane (SELEMION AMV) was studied to determine the selectivities of ionic species of phosphoric acid. The sorption of phosphoric acid by the membrane increased with increase in the phosphate concentration in the solution and pH. The sorption characteristics were successfully explained by the ion-exchange model considering the dissociation of phosphoric acid in the solution, electro-neutrality in the solution and in the membrane, and material balances of chemical species.

  6. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  7. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  8. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  9. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... Defluorinated Phosphoric Acid Subcategory § 422.50 Applicability; description of the defluorinated phosphoric... defluorination of phosphoric acid. Wet process phosphoric acid is dehydrated by application of heat and...

  10. Acid distribution in phosphoric acid fuel cells

    SciTech Connect

    Okae, I.; Seya, A.; Umemoto, M.

    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.

  11. Stabilizing platinum in phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Remick, R. J.

    1981-01-01

    The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst supported on a carbon substrate. During operation, the small platinum crystallites sinter, causing loss in cell performance. A support was developed that stabilizes platinum in the high surface area condition by retarding or preventing the sintering process. The approach is to form etch pits in the carbon by oxidizing the carbon in the presence of a metal oxide catalyst, remove the metal oxide by an acid wash, and then deposit platinum in these pits. Results confirm the formation of etch pits in each of the three supports chosen for investigation: Vulcan XC-72R, Vulcan XC-72 that was graphized at 2500 C, and Shawinigan Acetylene Black.

  12. World wide IFC phosphoric acid fuel cell implementation

    SciTech Connect

    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.

  13. Method for incorporating radioactive phosphoric acid solutions in concrete

    DOEpatents

    Wolf, G.A.; Smith, J.W.; Ihle, N.C.

    1982-07-08

    A method for incorporating radioactive phosphoric acid solutions in concrete is described wherein the phosphoric acid is reacted with Ca(OH)/sub 2/ to form a precipitate of hydroxyapatite and the hydroxyapatite is mixed with Portland cement to form concrete.

  14. Method for incorporating radioactive phosphoric acid solutions in concrete

    DOEpatents

    Wolf, Gary A [Kennewick, WA; Smith, Jeffrey W [Lancaster, OH; Ihle, Nathan C [Walla Walla, WA

    1984-01-01

    A method for incorporating radioactive phosphoric acid solutions in concrete is described wherein the phosphoric acid is reacted with Ca(OH).sub.2 to form a precipitate of hydroxyapatite and the hydroxyapatite is mixed with portland cement to form concrete.

  15. Potassium salts of hypodiphosphoric acid.

    PubMed

    Szafranowska, Barbara; Slepokura, Katarzyna; Lis, Tadeusz

    2012-12-01

    The synthesis and crystal structures of a series of six crystalline potassium salts of hypodiphosphoric acid, H(4)P(2)O(6), are reported, namely potassium hydrogen phosphonophosphonate, K(+)·H(3)P(2)O(6)(-), (I), dipotassium dihydrogen hypodiphosphate monohydrate, 2K(+)·H(2)P(2)O(6)(2-)·H(2)O, (II), dipotassium dihydrogen hypodiphosphate dihydrate, 2K(+)·H(2)P(2)O(6)(2-)·2H(2)O, (III), pentapotassium hydrogen hypodiphosphate dihydrogen hypodiphosphate dihydrate, 5K(+)·HP(2)O(6)(3-)·H(2)P(2)O(6)(2-)·2H(2)O, (IV), tripotassium hydrogen hypodiphosphate tetrahydrate, 3K(+)·HP(2)O(6)(3-)·4H(2)O, (V), and tetrapotassium hypodiphosphate tetrahydrate, 4K(+)·P(2)O(6)(4-)·4H(2)O, (VI). All the hypodiphosphate anions, viz. H(3)P(2)O(6)(-), H(2)P(2)O(6)(2-), HP(2)O(6)(3-) and P(2)O(6)(4-), adopt a staggered conformation. The P-P bond lengths [2.1722 (7)-2.1892 (10) Å] do not depend on the basicity of the anion. The compounds are organized into different types of one-, two- or three-dimensional polymeric hydrogen-bonded networks, or simply exist in the form of isolated or dimeric units. The coordination numbers of the K(+) cations range from 6 to 9, and the cationic sublattices are polymeric one-, two- or three-dimensional networks, or isolated [KO(6)] or dimeric [K(2)O(12)] polyhedra.

  16. Proton Conductivity in Phosphoric Acid: The Role of Quantum Effects

    DOE PAGES

    Heres, M.; Wang, Y.; Griffin, P. J.; ...

    2016-10-07

    Phosphoric acid has one of the highest intrinsic proton conductivities of any known liquids, and the mechanism of this exceptional conductivity remains a puzzle. In our detailed experimental studies we discovered a strong isotope effect in the conductivity of phosphoric acids caused by (i) a strong isotope shift of the glass transition temperature and (ii) a significant reduction of the energy barrier by zero-point quantum fluctuations. Our results suggest that the high conductivity in phosphoric acids is caused by a very efficient proton transfer mechanism, which is strongly assisted by quantum effects.

  17. Proton Conductivity in Phosphoric Acid: The Role of Quantum Effects

    NASA Astrophysics Data System (ADS)

    Heres, M.; Wang, Y.; Griffin, P. J.; Gainaru, C.; Sokolov, A. P.

    2016-10-01

    Phosphoric acid has one of the highest intrinsic proton conductivities of any known liquids, and the mechanism of this exceptional conductivity remains a puzzle. Our detailed experimental studies discovered a strong isotope effect in the conductivity of phosphoric acids caused by (i) a strong isotope shift of the glass transition temperature and (ii) a significant reduction of the energy barrier by zero-point quantum fluctuations. These results suggest that the high conductivity in phosphoric acids is caused by a very efficient proton transfer mechanism, which is strongly assisted by quantum effects.

  18. Arsenic removal from contaminated soil using phosphoric acid and phosphate.

    PubMed

    Zeng, Min; Liao, Bohan; Lei, Ming; Zhang, Yong; Zeng, Qingru; Ouyang, Bin

    2008-01-01

    Laboratory batch experiments were conducted to study arsenic (As) removal from a naturally contaminated soil using phosphoric acid (H3PO4) and potassium dihydrogen phosphate (KH2PO4). Both H3PO4 and KH2PO4 proved to reduce toxicity of the soil in terms of soil As content, attaining more than 20% As removal at a concentration of 200 mmol/L. At the same time, acidification of soil and dissolution of soil components (Ca, Mg, and Si) resulted from using these two extractants, especially H3PO4. The effectiveness of these two extractants could be attributed to the replacement of As by phosphate ions (PO4(3-)). The function of H3PO4 as an acid to dissolve soil components had little effects on As removal. KH2PO4 almost removed as much As as H3PO4, but it did not result in serious damage to soils, indicating that it was a more promising extractant. The results of a kinetic study showed that As removal reached equilibrium after incubation for 360 min, but dissolution of soil components, especially Mg and Ca, was very rapid. Therefore dissolution of soil components would be inevitable if As was further removed. Elovich model best described the kinetic data of As removal among the four models used in the kinetic study.

  19. Activated carbons prepared from phosphoric acid activation of grain sorghum.

    PubMed

    Diao, Yulu; Walawender, W P; Fan, L T

    2002-01-01

    The production of activated carbons from grain sorghum with phosphoric acid activation has been studied by means of two processes, i.e., one-stage and two-stage. The former comprises simultaneous carbonization and activation after impregnation; the latter, the carbonization of the precursor at 300 degrees C for 15 min, followed by the activation of the resultant char after impregnation with phosphoric acid. The preparation conditions, e.g., activation duration, phosphoric acid concentration, and activation temperature, have been varied to determine the optimal processing conditions. The optimal activation conditions for the highest surface areas have been determined to be 600 and 500 degrees C with a phosphoric acid concentration of 35% for the one-stage and two-stage processes, respectively. The two-stage process has been found to greatly enhance the porosity development, especially the microporosity.

  20. Materials characterization of phosphoric acid fuel cell system

    NASA Technical Reports Server (NTRS)

    Venkatesh, Srinivasan

    1986-01-01

    The component materials used in the fabrication of phosphoric acid fuel cells (PAFC) must have mechanical, chemical, and electrochemical stability to withstand the moderately high temperature (200 C) and pressure (500 kPa) and highly oxidizing nature of phosphoric acid. This study discusses the chemical and structural stability, performance and corrosion data on certain catalysts, catalyst supports, and electrode support materials used in PAFC applications.

  1. Materials characterization of phosphoric acid fuel cell system

    NASA Technical Reports Server (NTRS)

    Venkatesh, Srinivasan

    1986-01-01

    The component materials used in the fabrication of phosphoric acid fuel cells (PAFC) must have mechanical, chemical, and electrochemical stability to withstand the moderately high temperature (200 C) and pressure (500 kPa) and highly oxidizing nature of phosphoric acid. This study discusses the chemical and structural stability, performance and corrosion data on certain catalysts, catalyst supports, and electrode support materials used in PAFC applications.

  2. New applications for phosphoric acid fuel cells

    SciTech Connect

    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 co-generation, 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 is 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.

  3. New applications for phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    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.

  4. Phosphoric acid fuel cell platinum use study

    NASA Technical Reports Server (NTRS)

    Lundblad, H. L.

    1983-01-01

    The U.S. Department of Energy is promoting the private development of phosphoric acid fuel cell (PAFC) power plants for terrestrial applications. Current PAFC technology utilizes platinum as catalysts in the power electrodes. The possible repercussions that the platinum demand of PAFC power plant commercialization will have on the worldwide supply and price of platinum from the outset of commercialization to the year 2000 are investigated. The platinum demand of PAFC commercialization is estimated by developing forecasts of platinum use per unit of generating capacity and penetration of PAFC power plants into the electric generation market. The ability of the platinum supply market to meet future demands is gauged by assessing the size of platinum reserves and the capability of platinum producers to extract, refine and market sufficient quantities of these reserves. The size and timing of platinum price shifts induced by the added demand of PAFC commercialization are investigated by several analytical methods. Estimates of these price shifts are then used to calculate the subsequent effects on PAFC power plant capital costs.

  5. New applications for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  6. Phosphoric acid entrapment leads to apparent protein heterogeneity.

    PubMed

    Fountoulakis, M; Vilbois, F; Oesterhelt, G; Vetter, W

    1995-04-01

    Recombinant proteins produced in prokaryotes or eukaryotes show certain types of heterogeneity due to post-translational modifications. Some preparations of a soluble interferon gamma receptor, produced in Escherichia coli, appeared as a double band with slightly different mobilities in non-reducing sodium dodecylsulfate and native polyacrylamide gels. Ion spray mass spectrometry showed that the two forms had a mass difference of one to three multiples of 97 +/- 2 D. Gas chromatography-mass spectrometry analysis revealed the presence of phosphoric acid in the hydrolysate and in the intact protein. The more slowly migrating protein species had trapped molecules of phosphoric acid during the protein extraction. Most of the trapped phosphoric acid was loosely associated with the protein. One to three molecules were tightly, but non-covalently linked per receptor molecule. Phosphoric acid entrapment did not affect biological activity and most likely did not affect protein conformation. The species carrying phosphoric acid showed higher solubility. Trapping of phosphoric acid by proteins may be a general phenomenon and the results reported here thus useful in the characterization of other recombinant proteins.

  7. Nanosized hydroxyapatite powder synthesized from eggshell and phosphoric acid.

    PubMed

    Lee, Sang-Jin; Yoon, Young-Soo; Lee, Myung-Hyun; Oh, Nam-Sik

    2007-11-01

    The present research describes synthesis of highly sinterable, nano-sized hydroxyapatite (HAp) powders using a wet chemical route with recycled eggshell and phosphoric acid as calcium and phosphorous sources. The raw eggshell was easily turned to CaO by the calcining process, and phosphoric acid was mixed with the calcined eggshell by the wet, ball-milling method. The crystalline development and microstructures of the synthesized powders and sintered samples were examined by X-ray diffractometry and scanning electron microscopy, respectively. The observed phases on the powder synthesis process were dependent on the mixing ratio (wt%) of the calcined eggshell to phosphoric acid and the heating temperature. The ball-milled, nano-sized HAp powder, which has an average particle size of 70 nm, was fully densified at 1300 degrees C for 1h. The Ca/P ratio for stoichiometric composition of HAp was controlled by adjustment of the mixing ratio.

  8. 21 CFR 184.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Potassium acid tartrate. 184.1077 Section 184.1077... GRAS § 184.1077 Potassium acid tartrate. (a) Potassium acid tartrate (C4H5KO6, CAS Reg. No. 868-14-4) is the potassium acid salt of l−(+)−tartaric acid and is also called potassium bitartrate or cream of...

  9. Effect of dietary phosphoric acid supplementation on acid-base balance and mineral and bone metabolism in adult cats.

    PubMed

    Fettman, M J; Coble, J M; Hamar, D W; Norrdin, R W; Seim, H B; Kealy, R D; Rogers, Q R; McCrea, K; Moffat, K

    1992-11-01

    Experimental evidence indicates that maintenance of urinary pH < or = 6.4 is the single most effective means of preventing feline struvite crystalluria or urolithiasis of noninfectious causes. This may be accomplished by dietary acidification, but must be moderated to avoid potential adverse effects of excessive acidification, including bone demineralization, negative calcium balance, potassium depletion, and renal disease. Effects of chronic dietary phosphoric acid supplementation on acid-base balance and on mineral and bone metabolism were investigated in adult, domestic cats. One group of 6 cats was fed a basal, naturally acidifying diet without added acidifiers, and another group of 6 cats was fed 1.7% dietary phosphoric acid. Changes observed during 12 months of study included development of noncompensated metabolic acidosis, increased urinary calcium excretion, and lower but positive calcium balance in cats of both groups. Urinary pH decreased in cats of both groups, but was significantly (P < 0.05) and consistently maintained < or = 6.4 in cats given dietary phosphoric acid. Urinary phosphorus excretion increased in cats of both groups, but was significantly (P < 0.05) greater in phosphoric acid-supplemented cats, leading to lower overall phosphorus balance as well. Potassium balance decreased in cats of both groups, but was only transiently negative in the phosphoric acid-supplemented cats midway through the study, and normalized at positive values thereafter. Plasma taurine concentration was not affected by dietary acidification, and remained well within the acceptable reference range for taurine metabolism. Double labeling of bone in vivo with fluorescent markers was followed by bone biopsy and histomorphometric measurement of several static and dynamic variables of bone formation. Overall indices of bone formation decreased in cats of both groups with age and confinement, but were not affected by dietary phosphoric acid supplementation. Dietary

  10. 40 CFR 721.6200 - Fatty acid polyamine condensate, phosphoric acid ester salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Fatty acid polyamine condensate, phosphoric acid ester salts. 721.6200 Section 721.6200 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.6200 Fatty acid polyamine condensate, phosphoric acid...

  11. 40 CFR 721.6200 - Fatty acid polyamine condensate, phosphoric acid ester salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fatty acid polyamine condensate, phosphoric acid ester salts. 721.6200 Section 721.6200 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.6200 Fatty acid polyamine condensate, phosphoric acid...

  12. 40 CFR 721.6200 - Fatty acid polyamine condensate, phosphoric acid ester salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Fatty acid polyamine condensate, phosphoric acid ester salts. 721.6200 Section 721.6200 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.6200 Fatty acid polyamine condensate, phosphoric acid...

  13. 40 CFR 721.6200 - Fatty acid polyamine condensate, phosphoric acid ester salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fatty acid polyamine condensate, phosphoric acid ester salts. 721.6200 Section 721.6200 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.6200 Fatty acid polyamine condensate, phosphoric acid...

  14. Phosphoric acid impurities in phosphoric acid fuel cell electrolytes. 2: Effects on the oxygen reduction reaction at platinum electrodes

    SciTech Connect

    Sugishima, Noboru; Hinatsu, J.T.; Foulkes, F.R. . Dept. of Chemical Engineering and Applied Chemistry)

    1994-12-01

    The effects of phosphorus acid additions on the oxygen reduction reaction at platinum electrodes in concentrated phosphoric acid were studied. The oxygen reduction currents decreased, and the Tafel slopes became more negative upon the addition of small concentrations of phosphorus acid. In addition,the phosphorus acid oxidation current tended to complete with the oxygen reduction current. These effects became more pronounced at higher phosphorus acid concentrations and at higher temperatures. Upon the addition of phosphorus acid the number of electrons involved in the oxygen reduction reaction decreased from a value close to four to a value approaching two, suggesting promotion of a two-electron reduction to peroxide. Therefore, in studies of the electrochemical reduction of oxygen in hot concentrated phosphoric acid or in fuel cell systems using hot concentrated phosphoric acid as electrolyte, it is recommended that precautions be taken against the inadvertent formation of the phosphorus acid. The removal of phosphorus acid from concentrated phosphoric acid by repeated potential cycling at 100 mV/s between + 0.5 and +1.50 V (vs. dynamic hydrogen electrode) was demonstrated.

  15. Recovery of uranium from wet-process phosphoric acid

    SciTech Connect

    Berry, W.W.; Henrickson, A.V.

    1981-11-24

    Uranium values are recovered as uranyl peroxide from wet process phosphoric acid by a solvent extraction-precipitation process. The preferred form of this process comprises a first solvent extraction with depa-topo followed by reductive stripping of the extractant with fe++ - containing phosphoric acid. After reoxidation, the uranium-containing aqueous stripping solution is extracted again with depa-topo and the pregnant organic is then stripped with a dilute ammonium carbonate solution. The resulting ammonium uranyl tricarbonate solution is then acidified, with special kerosene treatment to prevent wax formation, and the acidified solution is reacted with H/sub 2/O/sub 2/ to precipitate a uranyl peroxide compound.

  16. Technology development for phosphoric acid fuel cell powerplant (phase 2)

    NASA Technical Reports Server (NTRS)

    Christner, L.

    1979-01-01

    The status of technology for the manufacturing and testing of 1200 sq. cm cell materials, components, and stacks for on-site integrated energy systems is assessed. Topics covered include: (1) preparation of thin layers of silicon carbide; (2) definition and control schemes for volume changes in phosphoric acid fuel cells; (3) preparation of low resin content graphite phenolic resin composites; (4) chemical corrosion of graphite-phenolic resin composites in hot phosphoric acid; (5) analysis of electrical resistance of composite materials for fuel cells; and (6) fuel cell performance and testing.

  17. 21 CFR 184.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Potassium acid tartrate. 184.1077 Section 184.1077... Listing of Specific Substances Affirmed as GRAS § 184.1077 Potassium acid tartrate. (a) Potassium acid tartrate (C4H5KO6, CAS Reg. No. 868-14-4) is the potassium acid salt of l−(+)−tartaric acid and is also...

  18. 21 CFR 184.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Potassium acid tartrate. 184.1077 Section 184.1077... Listing of Specific Substances Affirmed as GRAS § 184.1077 Potassium acid tartrate. (a) Potassium acid tartrate (C4H5KO6, CAS Reg. No. 868-14-4) is the potassium acid salt of l−(+)−tartaric acid and is also...

  19. 21 CFR 184.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium acid tartrate. 184.1077 Section 184.1077... Listing of Specific Substances Affirmed as GRAS § 184.1077 Potassium acid tartrate. (a) Potassium acid tartrate (C4H5KO6, CAS Reg. No. 868-14-4) is the potassium acid salt of l−(+)−tartaric acid and is also...

  20. 21 CFR 184.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Potassium acid tartrate. 184.1077 Section 184.1077... Listing of Specific Substances Affirmed as GRAS § 184.1077 Potassium acid tartrate. (a) Potassium acid tartrate (C4H5KO6, CAS Reg. No. 868-14-4) is the potassium acid salt of l−(+)−tartaric acid and is also...

  1. Corrosion of graphite composites in phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Christner, L. G.; Dhar, H. P.; Farooque, M.; Kush, A. K.

    1986-01-01

    Polymers, polymer-graphite composites and different carbon materials are being considered for many of the fuel cell stack components. Exposure to concentrated phosphoric acid in the fuel cell environment and to high anodic potential results in corrosion. Relative corrosion rates of these materials, failure modes, plausible mechanisms of corrosion and methods for improvement of these materials are investigated.

  2. Corrosion of graphite composites in phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Christner, L. G.; Dhar, H. P.; Farooque, M.; Kush, A. K.

    1986-01-01

    Polymers, polymer-graphite composites and different carbon materials are being considered for many of the fuel cell stack components. Exposure to concentrated phosphoric acid in the fuel cell environment and to high anodic potential results in corrosion. Relative corrosion rates of these materials, failure modes, plausible mechanisms of corrosion and methods for improvement of these materials are investigated.

  3. 46 CFR 153.558 - Special requirements for phosphoric acid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and... containment system must be: (a) Lined with natural rubber or neoprene; (b) Lined with a material approved for phosphoric acid tanks by the Commandant (CG-ENG); or (c) Made of a stainless steel that resists corrosion by...

  4. 21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Partial phosphoric acid esters of polyester resins... COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.260 Partial phosphoric acid esters of polyester resins. Partial phosphoric acid esters of polyester resins identified in this section...

  5. 40 CFR 721.10220 - Phosphoric acid, polymer with cycloaliphatic diglycidyl ether, alkylethers (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphoric acid, polymer with... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10220 Phosphoric acid, polymer with... to reporting. (1) The chemical substance identified generically as phosphoric acid, polymer with...

  6. 40 CFR 721.10140 - Phosphoric acid, tin (2+) salt (2:3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphoric acid, tin (2+) salt (2:3... Specific Chemical Substances § 721.10140 Phosphoric acid, tin (2+) salt (2:3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as phosphoric acid, tin (2...

  7. 21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Partial phosphoric acid esters of polyester resins... COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.260 Partial phosphoric acid esters of polyester resins. Partial phosphoric acid esters of polyester resins identified in this section...

  8. 21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Partial phosphoric acid esters of polyester resins... COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.260 Partial phosphoric acid esters of polyester resins. Partial phosphoric acid esters of polyester resins identified in this section...

  9. 21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Partial phosphoric acid esters of polyester resins... COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.260 Partial phosphoric acid esters of polyester resins. Partial phosphoric acid esters of polyester resins identified in this section...

  10. 40 CFR 721.10220 - Phosphoric acid, polymer with cycloaliphatic diglycidyl ether, alkylethers (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphoric acid, polymer with... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10220 Phosphoric acid, polymer with... to reporting. (1) The chemical substance identified generically as phosphoric acid, polymer...

  11. 21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Partial phosphoric acid esters of polyester resins... Components of Coatings § 175.260 Partial phosphoric acid esters of polyester resins. Partial phosphoric acid esters of polyester resins identified in this section and applied on aluminum may be safely used as...

  12. 40 CFR 721.10220 - Phosphoric acid, polymer with cycloaliphatic diglycidyl ether, alkylethers (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, polymer with... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10220 Phosphoric acid, polymer with... to reporting. (1) The chemical substance identified generically as phosphoric acid, polymer with...

  13. 40 CFR 721.10220 - Phosphoric acid, polymer with cycloaliphatic diglycidyl ether, alkylethers (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid, polymer with... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10220 Phosphoric acid, polymer with... to reporting. (1) The chemical substance identified generically as phosphoric acid, polymer with...

  14. 21 CFR 582.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Potassium acid tartrate. 582.1077 Section 582.1077 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1077 Potassium acid tartrate. (a) Product. Potassium acid tartrate. (b) Conditions of use...

  15. 21 CFR 582.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Potassium acid tartrate. 582.1077 Section 582.1077 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1077 Potassium acid tartrate. (a) Product. Potassium acid tartrate. (b) Conditions of use...

  16. 21 CFR 582.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Potassium acid tartrate. 582.1077 Section 582.1077 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1077 Potassium acid tartrate. (a) Product. Potassium acid tartrate. (b) Conditions of use...

  17. 21 CFR 582.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium acid tartrate. 582.1077 Section 582.1077 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1077 Potassium acid tartrate. (a) Product. Potassium acid tartrate. (b) Conditions of use...

  18. 21 CFR 582.1077 - Potassium acid tartrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Potassium acid tartrate. 582.1077 Section 582.1077 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1077 Potassium acid tartrate. (a) Product. Potassium acid tartrate. (b) Conditions of use...

  19. Radiation hardness of the storage phosphor europium doped potassium chloride for radiation therapy dosimetry

    SciTech Connect

    Driewer, Joseph P.; Chen, Haijian; Osvet, Andres; Low, Daniel A.; Li, H. Harold

    2011-08-15

    Purpose: An important property of a reusable dosimeter is its radiation hardness, that is, its ability to retain its dosimetric merits after irradiation. The radiation hardness of europium doped potassium chloride (KCl:Eu{sup 2+}), a storage phosphor material recently proposed for radiation therapy dosimetry, is examined in this study. Methods: Pellet-style KCl:Eu{sup 2+} dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The pellets were exposed by a 6 MV photon beam or in a high dose rate {sup 137}Cs irradiator. Macroscopic properties, such as radiation sensitivity, dose response linearity, and signal stability, were studied with a laboratory photostimulated luminescence (PSL) readout system. Since phosphor performance is related to the state of the storage centers and the activator, Eu{sup 2+}, in the host lattice, spectroscopic and temporal measurements were carried out in order to explore radiation-induced changes at the microscopic level. Results: KCl:Eu{sup 2+} dosimeters retained approximately 90% of their initial signal strength after a 5000 Gy dose history. Dose response was initially supralinear over the dose range of 100-700 cGy but became linear after 60 Gy. Linearity did not change significantly in the 0-5000 Gy dose history spanned in this study. Annealing high dose history chips resulted in a return of supralinearity and a recovery of sensitivity. There were no significant changes in the PSL stimulation spectra, PSL emission spectra, photoluminescence spectra, or luminescence lifetime, indicating that the PSL signal process remains intact after irradiation but at a reduced efficiency due to reparable radiation-induced perturbations in the crystal lattice. Conclusions: Systematic studies of KCl:Eu{sup 2+} material are important for understanding how the material can be optimized for radiation therapy dosimetry purposes. The data presented here indicate that KCl:Eu{sup 2+} exhibits strong radiation hardness and

  20. A mechanistic study of copper electropolishing in phosphoric acid solutions

    NASA Astrophysics Data System (ADS)

    Mansson, Andrew

    The microelectronics industry is using copper as the interconnect material for microchips. A study of copper electropolishing is important for the process development of a new, low downforce approach, which is being developed to replace chemical mechanical polishing (CMP) of the copper overburden. A promising technology is a combination of electropolishing with conventional CMP. Electropolishing of copper in phosphoric acid has been studied for, more than 70 years. Previous work has shown that the polishing rate, as measured by current density is directly related to the viscosity of the electrolyte. Also, the limiting species is water. In this study, a multidimensional design of experiments was performed to develop an in-depth model of copper electropolishing. Phosphoric acid was mixed with alcohols of different molecular weight and related viscosity to investigate how the solvents' properties affected polishing. The alcohols used were methanol, ethanol, isopropanol, butanol, ethylene glycol, and glycerol. The limiting current densities and electrochemical behavior of each solution was measured by potentiodynamic and potentiostatic experiments. Also, the kinematic viscosity and density were measured to determine the dynamic viscosity to investigate the relationship of current density and viscosity. Water, methanol, ethanol, and isopropanol solutions were also examined at 20°C to 60°C. Next, the relative percentage of dissociated phosphoric acid was measured by Raman spectroscopy for each polishing solution. Raman spectroscopy was also used to measure the relative dissociation of phosphoric acid inside the polishing film. Additionally, wafers were electropolished and electrochemical mechanically polished to investigate the effects of the different solvents, fluid flow, current, and potential. The results of these experiments have shown that the molecular mass and the ability of the solvent to dissociate phosphoric acid are the primary electrolyte properties that

  1. Synthesis of novel acid electrolytes for phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Adcock, James L.

    1988-11-01

    A 40 millimole per hour scale aerosol direct fluorination reactor was constructed. F-Methyl F-4-methoxybutanoate and F-4-methoxybutanoyl fluoride were synthesized by aerosol direct fluorination of methyl 4-methoxybutanoate. Basic hydrolysis of the perfluorinated derivatives produce sodium F-4 methoxybutanoate which was pyrolyzed to F-3-methoxy-1-propene. Purification and shipment of 33 grams of F-3-methoxy-1-propene followed. Syntheses by analogous methods allowed production and shipment of 5 grams of F-3-ethoxy 1-propene, 18 grams of F-3-(2-methoxy.ethoxy) 1-propene, and 37 grams of F-3,3-dimethyl 1-butene. Eighteen grams of F-2,2-dimethyl 1-chloropropane was produced directly and shipped. As suggested by other contractors, 5 grams of F-3-methoxy 1-iodopropane, and 5 grams of F-3-(2-methoxy.ethoxy) 1-iodopropane were produced by converting the respective precursor acid sodium salts produced for olefin synthesis to the silver salts and pyrolyzing them with iodine. Each of these compounds was prepared for the first time by the aerosol fluorination process during the course of the contract. These samples were provided to other Gas Research Institute (GRI) contractors for synthesis of perfluorinated sulfur (VI) and phosphorous (V) acids.

  2. PROCESS FOR RECOVERING URANIUM FROM AQUEOUS PHOSPHORIC ACID LIQUORS

    DOEpatents

    Schmitt, J.M.

    1962-09-01

    A liquid-liquid extraction method is given for recovering uranium values from aqueous solutions. An acidic aqueous solution containing uranium values is contacted with an organic phase comprising an organic diluent and the reaction product of phosphorous pentoxide and a substantially pure dialkylphosphoric acid. The uranium values are transferred to the organic phase even from aqueous solutions containing a high concentration of strong uranium complexing agents such as phosphate ions. (AEC)

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

    SciTech Connect

    Oh, George N.; Burns, Peter C.

    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

  4. 40 CFR 721.7375 - Potassium salt of polyolefin acid.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Potassium salt of polyolefin acid. 721... Substances § 721.7375 Potassium salt of polyolefin acid. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a potassium salt of polyolefin...

  5. 40 CFR 721.7375 - Potassium salt of polyolefin acid.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Potassium salt of polyolefin acid. 721... Substances § 721.7375 Potassium salt of polyolefin acid. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a potassium salt of polyolefin...

  6. 40 CFR 721.7375 - Potassium salt of polyolefin acid.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Potassium salt of polyolefin acid. 721... Substances § 721.7375 Potassium salt of polyolefin acid. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a potassium salt of polyolefin...

  7. 40 CFR 721.7375 - Potassium salt of polyolefin acid.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Potassium salt of polyolefin acid. 721... Substances § 721.7375 Potassium salt of polyolefin acid. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a potassium salt of polyolefin...

  8. 40 CFR 721.7375 - Potassium salt of polyolefin acid.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Potassium salt of polyolefin acid. 721... Substances § 721.7375 Potassium salt of polyolefin acid. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a potassium salt of polyolefin...

  9. Enzymatic saccharification coupling with polyester recovery from cotton-based waste textiles by phosphoric acid pretreatment.

    PubMed

    Shen, Fei; Xiao, Wenxiong; Lin, Lili; Yang, Gang; Zhang, Yanzong; Deng, Shihuai

    2013-02-01

    In order to recycle the cotton-based waste textiles, a novel process was designed for pretreating waste textiles with phosphoric acid to recover polyester and fermentable sugar. The effects of pretreatment conditions including, phosphoric acid concentration, pretreatment temperature, time, and ratio of textiles and phosphoric acid were thoroughly investigated. Results indicated the mentioned four factors had significant influences on sugar and polyester recovery. Almost complete polyester recovery was achieved by enhancing phosphoric acid concentration, temperature and pretreatment time or reducing the ratio of textiles and phosphoric acid. However, these behaviors decreased the sugar recovery seriously. 100% polyester recovery with a maximum sugar recovery of 79.2% was achieved at the optimized conditions (85% phosphoric acid, 50°C, 7h, and the ratio of 1:15). According to the technical and cost-benefit analysis, it was technically feasible and potentially profitable to recover polyester and sugar from waste textiles by phosphoric acid pretreatment.

  10. Methodology for detecting residual phosphoric acid in polybenzoxazole fibers.

    PubMed

    Park, Eun Su; Sieber, John; Guttman, Charles; Rice, Kirk; Flynn, Kathleen; Watson, Stephanie; Holmes, Gale

    2009-12-01

    Because of the premature failure of in-service soft-body armor containing the ballistic fiber poly[(benzo-[1,2-d:5,4-d']-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), the Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology (NIST) initiated a research program to investigate the reasons for this failure and to develop testing methodologies and protocols to ensure that these types of failures do not reoccur. In a report that focused on the stability of the benzoxazole ring that is characteristic of PBO fibers, Holmes, G. A.; Rice, K.; Snyder, C. R. J. Mater. Sci. 2006, 41, 4105-4116, showed that the benzoxazole ring was susceptible to hydrolytic degradation under acid conditions. Because of the processing conditions for the fibers, it is suspected by many researchers that residual phosphoric acid may cause degradation of the benzoxazole ring resulting in a reduction of ballistic performance. Prior to this work, no definitive data have indicated the presence of phosphoric acid since the residual phosphorus is not easily extracted and the processed fibers are known to incorporate phosphorus containing processing aids. Methods to efficiently extract phosphorus from PBO are described in this article. Further, characterization determined that the majority of the extractable phosphorus in PBO was attributed to the octyldecyl phosphate processing aid with some phosphoric acid being detected. Analysis by matrix assisted laser desorption ionization of model PBO oligomers indicates that the nonextractable phosphorus is attached to the PBO polymer chain as a monoaryl phosphate ester. The response of model aryl phosphates to NaOH exposure indicates that monoaryl phosphate ester is stable to NaOH washes used in the manufacturing process to neutralize the phosphoric acid reaction medium and to extract residual phosphorus impurities.

  11. Integral edge seals for phosphoric acid fuel cells

    DOEpatents

    Granata, Jr., Samuel J.; Woodle, Boyd M.; Dunyak, Thomas J.

    1992-01-01

    A phosphoric acid fuel cell having integral edge seals formed by an elastomer permeating an outer peripheral band contiguous with the outer peripheral edges of the cathode and anode assemblies and the matrix to form an integral edge seal which is reliable, easy to manufacture and has creep characteristics similar to the anode, cathode and matrix assemblies inboard of the seals to assure good electrical contact throughout the life of the fuel cell.

  12. Status of commercial phosphoric acid fuel cell system development

    NASA Technical Reports Server (NTRS)

    Warshay, M.; Prokopius, P. R.; Simons, S. N.; King, R. B.

    1981-01-01

    A review of the current commercial phosphoric acid fuel cell system development efforts is presented. In both the electric utility and on-site integrated energy system applications, reducing cost and increasing reliability are important. The barrier to the attainment of these goals has been materials. The differences in approach among the three major participants are their technological features, including electrodes, matrices, intercell cooling, bipolar/separator plates, electrolyte management, fuel selection and system design philosophy.

  13. Integral edge seals for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Granata, Jr., Samuel J. (Inventor); Woodle, Boyd M. (Inventor); Dunyak, Thomas J. (Inventor)

    1992-01-01

    A phosphoric acid fuel cell having integral edge seals formed by an elastomer permeating an outer peripheral band contiguous with the outer peripheral edges of the cathode and anode assemblies and the matrix to form an integral edge seal which is reliable, easy to manufacture and has creep characteristics similar to the anode, cathode and matrix assemblies inboard of the seals to assure good electrical contact throughout the life of the fuel cell.

  14. Status of commercial phosphoric acid fuel cell system development

    NASA Technical Reports Server (NTRS)

    Warshay, M.; Prokopius, P. R.; Simons, S. N.; King, R. B.

    1981-01-01

    A review of the current commercial phosphoric acid fuel cell system development efforts is presented. In both the electric utility and on-site integrated energy system applications, reducing cost and increasing reliability are important. The barrier to the attainment of these goals has been materials. The differences in approach among the three major participants are their technological features, including electrodes, matrices, intercell cooling, bipolar/separator plates, electrolyte management, fuel selection and system design philosophy.

  15. Improvement of Phosphoric Acid Fuel Cell Stacks.

    DTIC Science & Technology

    1980-07-01

    cell stacks. Stack assembly techniques using both prefilled and dry matrices with wick filling were employed with equally good results. Phenolic fiber...matrix to provide edge sealing, with no cement being used (except to position the electrodes on the bipolar plate). The stack is assembled with prefilled ...used in the wet assembly technique. Prior to use, the acid is heated to 170 0F. Next, 16 to 20 ml of acid is applied by syringe uniformly over the 5 in

  16. Cathode catalysts for primary phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Alkylation or carbon Vulcan XC-72, the support carbon, was shown to provide the most stable bond type for linking cobalt dehydrodibenzo tetraazannulene (CoTAA) to the surface of the carbon; this result is based on data obtained by cyclic voltammetry, pulse voltammetry and by release of 14C from bonded CoTAA. Half-cell tests at 100 C in 85% phosphoric acid showed that CoTAA bonded to the surface of carbon (Vulcan XC-72) via an alkylation procedure is a more active catalyst than is platinum based on a factor of two improvement in Tafel slope; dimeric CoTAA had catalytic activity equal to platinum. Half-cell tests also showed that bonded CoTAA catalysts do not suffer a loss in potential when air is used as a fuel rather than oxygen. Commercially available polytetrafluroethylene (PTFE) was shown to be unstable in the fuel cell environment with degradation occurring in 2000 hours or less. The PTFE was stressed at 200 C in concentrated phosphoric acid as well as electrochemically stressed in 150 C concentrated phosphoric acid; the surface chemistry of PTFE was observed to change significantly. Radiolabeled PTFE was prepared and used to verify that such chemical changes also occur in the primary fuel cell environment.

  17. Sodium and Potassium Interactions with Nucleic Acids.

    PubMed

    Auffinger, Pascal; D'Ascenzo, Luigi; Ennifar, Eric

    2016-01-01

    Metal ions are essential cofactors for the structure and functions of nucleic acids. Yet, the early discovery in the 70s of the crucial role of Mg(2+) in stabilizing tRNA structures has occulted for a long time the importance of monovalent cations. Renewed interest in these ions was brought in the late 90s by the discovery of specific potassium metal ions in the core of a group I intron. Their importance in nucleic acid folding and catalytic activity is now well established. However, detection of K(+) and Na(+) ions is notoriously problematic and the question about their specificity is recurrent. Here we review the different methods that can be used to detect K(+) and Na(+) ions in nucleic acid structures such as X-ray crystallography, nuclear magnetic resonance or molecular dynamics simulations. We also discuss specific versus non-specific binding to different structures through various examples.

  18. Phosphoric Acid-Mediated Synthesis of Vinyl Sulfones through Decarboxylative Coupling Reactions of Sodium Sulfinates with Phenylpropiolic Acids.

    PubMed

    Rong, Guangwei; Mao, Jincheng; Yan, Hong; Zheng, Yang; Zhang, Guoqi

    2015-08-07

    A novel phosphoric acid -mediated synthesis of vinyl sulfones through decarboxylative coupling reactions of sodium sulfinates with phenylpropiolic acids is described. This transformation is efficient and environmentally friendly.

  19. Energy recovery method and system for combined sulphuric acid and phosphoric acid manufacturing plant

    SciTech Connect

    Cameron, G. M.; Orlando, J. V.

    1985-01-22

    In conventional processes for manufacturing phosphoric acid, sulphuric acid is reacted with phosphate rock to produce weak phosphoric acid which is concentrated using steam from the associated sulphuric acid manufacturing operation. Low grade heat from the absorbers and drier of the sulphuric acid manufacturing plant has been wasted. According to the invention waste heat from the drier and one or more absorbers of the sulphuric acid manufacturing plant is used in all the evaporators of the phosphoric acid plant. The evaporators all operate at low pressures and their heaters are arranged in series, to enable the heat to be used at the relatively low temperatures available. The valuable steam is thus freed for other uses.

  20. Full scale phosphoric acid fuel cell stack technology development

    NASA Technical Reports Server (NTRS)

    Christner, L.; Faroque, M.

    1984-01-01

    The technology development for phosphoric acid fuel cells is summarized. The preparation, heat treatment, and characterization of carbon composites used as bipolar separator plates are described. Characterization included resistivity, porosity, and electrochemical corrosion. High density glassy carbon/graphite composites performed well in long-term fuel cell endurance tests. Platinum alloy cathode catalysts and low-loaded platinum electrodes were evaluated in 25 sq cm cells. Although the alloys displayed an initial improvement, some of this improvement diminished after a few thousand hours of testing. Low platinum loading (0.12 mg/sq cm anodes and 0.3 mg/sq cm cathodes) performed nearly as well as twice this loading. A selectively wetproofed anode backing paper was tested in a 5 by 15 inch three-cell stack. This material may provide for acid volume expansion, acid storage, and acid lateral distribution.

  1. Fact Sheet - Phosphate Fertilizer Production Plants and Phosphoric Acid Manufacturing Plants NESHAP

    EPA Pesticide Factsheets

    Fact sheet summarizing National Emission Standards for Hazardous Air Pollutants (NESHAP) for Phosphate Fertilizer Production Plants and Phosphoric Acid Manufacturing Plants (40 CFR 63 Subparts AA and BB).

  2. Phosphoric acid, nitric acid, and hydrogen peroxide digestion of soil and plant materials for selenium determination

    SciTech Connect

    Dong, A.; Rendig, V.V.; Burau, R.G.; Besga, G.S.

    1987-11-15

    A mixture of phosphoric acid, nitric acid, and hydrogen peroxide has been proposed as an alternative to the use of the nitric/perchloric acid mixture to digest biological fluids to determine their selenium (Se) content. The purpose of the studies reported here was to test the applicability of this digestion method for the determination of Se in soil and plant materials.

  3. 40 CFR 721.10177 - Phosphoric acid, yttrium(3+) salt (1:1).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphoric acid, yttrium(3+) salt (1:1... Specific Chemical Substances § 721.10177 Phosphoric acid, yttrium(3+) salt (1:1). (a) Chemical substance... acid, yttrium(3+) salt (1:1) (PMN P-04-153; CAS No. 13990-54-0) is subject to reporting under this...

  4. 40 CFR 721.10177 - Phosphoric acid, yttrium(3+) salt (1:1).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, yttrium(3+) salt (1:1... Specific Chemical Substances § 721.10177 Phosphoric acid, yttrium(3+) salt (1:1). (a) Chemical substance... acid, yttrium(3+) salt (1:1) (PMN P-04-153; CAS No. 13990-54-0) is subject to reporting under...

  5. 40 CFR 721.10177 - Phosphoric acid, yttrium(3+) salt (1:1).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid, yttrium(3+) salt (1:1... Specific Chemical Substances § 721.10177 Phosphoric acid, yttrium(3+) salt (1:1). (a) Chemical substance... acid, yttrium(3+) salt (1:1) (PMN P-04-153; CAS No. 13990-54-0) is subject to reporting under...

  6. 40 CFR 721.10177 - Phosphoric acid, yttrium(3+) salt (1:1).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphoric acid, yttrium(3+) salt (1:1... Specific Chemical Substances § 721.10177 Phosphoric acid, yttrium(3+) salt (1:1). (a) Chemical substance... acid, yttrium(3+) salt (1:1) (PMN P-04-153; CAS No. 13990-54-0) is subject to reporting under...

  7. 40 CFR 721.10177 - Phosphoric acid, yttrium(3+) salt (1:1).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid, yttrium(3+) salt (1:1... Specific Chemical Substances § 721.10177 Phosphoric acid, yttrium(3+) salt (1:1). (a) Chemical substance... acid, yttrium(3+) salt (1:1) (PMN P-04-153; CAS No. 13990-54-0) is subject to reporting under...

  8. Commercial phosphoric acid fuel cell system technology development

    NASA Technical Reports Server (NTRS)

    Prokopius, P. R.; Warshay, M.; Simons, S. N.; King, R. B.

    1979-01-01

    A review of the current commercial phosphoric acid fuel cell system technology development efforts is presented. In both the electric utility and on-site integrated energy system applications, reducing cost and increasing reliability are the technology drivers at this time. The longstanding barrier to the attainment of these goals, which manifests itself in a number of ways, has been materials. The differences in approach among the three major participants (United Technologies Corporation (UTC), Westinghouse Electric Corporation/Energy Research Corporation (ERC), and Engelhard Industries) and their unique technological features, including electrodes, matrices, intercell cooling, bipolar/separator plates, electrolyte management, fuel selection and system design philosophy are discussed.

  9. Technology Development for Phosphoric Acid Fuel Cell Powerplant, Phase 2

    NASA Technical Reports Server (NTRS)

    Christner, L.

    1980-01-01

    The technology development for materials, cells, and reformers for on site integrated energy systems is described. The carbonization of 25 cu cm, 350 cu cm, and 1200 cu cm cell test hardware was accomplished and the performance of 25 cu cm fuel cells was improved. Electrochemical corrosion rates of graphite/phenolic resin composites in phosphoric acid were determined. Three cells (5 in by 15 in stacks) were operated for longer than 7000 hours. Specified endurance stacks completed a total of 4000 hours. An electrically heated reformer was tested and is to provide hydrogen for 23 cell fuel cell stack.

  10. Catalyst and electrode research for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Antoine, A. C.; King, R. B.

    1987-01-01

    An account is given of the development status of phosphoric acid fuel cells' high performance catalyst and electrode materials. Binary alloys have been identified which outperform the baseline platinum catalyst; it has also become apparent that pressurized operation is required to reach the desired efficiencies, calling in turn for the use of graphitized carbon blacks in the role of catalyst supports. Efforts to improve cell performance and reduce catalyst costs have led to the investigation of a class of organometallic cathode catalysts represented by the tetraazaannulenes, and a mixed catalyst which is a mixture of carbons catalyzed with an organometallic and a noble metal.

  11. Catalyst and electrode research for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Antoine, A. C.; King, R. B.

    1987-01-01

    An account is given of the development status of phosphoric acid fuel cells' high performance catalyst and electrode materials. Binary alloys have been identified which outperform the baseline platinum catalyst; it has also become apparent that pressurized operation is required to reach the desired efficiencies, calling in turn for the use of graphitized carbon blacks in the role of catalyst supports. Efforts to improve cell performance and reduce catalyst costs have led to the investigation of a class of organometallic cathode catalysts represented by the tetraazaannulenes, and a mixed catalyst which is a mixture of carbons catalyzed with an organometallic and a noble metal.

  12. The relationship between uric acid and potassium in normal subjects.

    PubMed Central

    Kennedy, A C; Boddy, K; King, P C; Brennan, J; Anderson, J A; Buchanan, W W

    1978-01-01

    The serum uric acid concentration in normal healthy subjects has been studied in relation to sex, height, weight, lean body mass measured from total body potassium and predicted from the Hume-Weyers formula (1971), total body potassium, plasma potassium and urea, and packed cell volume. The strongest correlation was found with sex, but height, weight, total body potassium, lean body mass (measured and predicted) also correlated significantly with serum uric acid concentration. However, when the sex variable was removed, the other factors lost their significant correlation. Finally, total red blood cell and plasma volumes were predicted (Hume and Goldberg, 1964) and from these an estimate of total plasma uric acid, total plasma potassium, and total red blood cell potassium obtained. Measured total body potassium was found to correlate well with total plasma potassium and total red blood cell potassium independent of sex. Total plasma uric acid correlated well with measured total body potassium when both sexes were considered and when separated into male and female groups the males retained a significant correlation as did the female group. PMID:686865

  13. Nitrogen, Phosphor, and Potassium Level in Soil and Oil Palm Tree at various Composition of plant species mixtures grown

    NASA Astrophysics Data System (ADS)

    Hanum, C.; Rauf, A.; Fazrin, D. A.; Habibi, A. R.

    2016-08-01

    In productive oil palm plantation areas, poor vegetation is generally caused by low light intensity. This condition causes excessive erosion and decreases soil fertility. One of the efforts for soil and water conservation at oil palm plantations is through increased vegetation diversity. The changes of soil and plant nitrogen, phosporus, and potassium content, observed by planting two types of herbs under oil palm tree, with different compositions. Vegetation composition was set as: Arachis glabrata 100%; Stenotaprum secundatum 100%; Arachis glabrata 50% + Stenotaprum secundatum 50%; Arachis glabrata 75% + Stenotaprum secundatum 25%; Arachis glabrata 25% + Stenotaprum secundatum 75%. The shoot and root fresh/dry weight, nutrient content (nitrogen, phosphor, and potassium) of each cutting were measured at the end of the experiment. Ten of treatment plant were harvested and divided shoots and roots after washing out of soil. Biomass samples were dried at 70 °C for 48 h and weighed. The total N and its proportional concentration (N%) were analyzed with the micro- Kjeldahl method. Potasium analyzing with flamephotometry, and phosphor and from samples was determined by analyzing with spectrophotometry method. The results showed the highest shoot growth of A.glabarata if planting was mixed with S. secundatum, but the result was different with S.secundatum being superior if planted with monoculture system. Combination of interrow cultivation is more recommended for soil conservation and nutrient maintenance in palm oil trees were A. Glabarata 75% + S.secundatum 25%.

  14. Technology development for phosphoric acid fuel cell powerplant, phase 2

    NASA Technical Reports Server (NTRS)

    Christner, L.

    1979-01-01

    Component development has resulted in routine molding of 12 in. by 17 in. bipolar plates with 80 percent acceptance. A 5 C per hour post-cure heating cycle for these plates was found to give blister free materials. Lowering the resin in a bipolar plate content from 32 percent to 22 percent decreases the resistivity more than 50 percent. Evaluation of the corrosion resistance of Novolak and Resol resins at 185 C in phosphoric acid indicates a slow etch. aerosol modified phenolics, however, decompose rapidly. Estimates of acid loss by the use of analytical expressions known as Margule, van Laar, and Wilson equations were not satisfactory. Experimental evaluation of the P4O10 vapor concentration of 103 wt percent acid at 191 C provided a value of 2 ppm. This value is based on a single experiment.

  15. Nitric-phosphoric acid treatment of TRU wastes

    SciTech Connect

    Smith, J.R.; Pierce, R.A.; Sturcken, E.F.

    1993-09-30

    A general process is being developed for the treatment of solid TRU and hazardous organic waste. Experimental data indicates that 100 lb/hr of aliphatic organic (plastics) and 1,000 lb/hr of non-aliphatic organic compounds can be quantitatively oxidized in a 1,000 gallon reaction vessel. The process uses dilute nitric acid in a concentrated phosphoric acid media as the main oxidant for the organic compounds. Phosphoric acid allows oxidation at temperatures up to 200{degrees}C and is relatively non-corrosive on 304-L stainless steel, especially at room temperature. Many organic materials have been completely oxidized to CO{sub 2}, CO, and inorganic acids in a 0.1M HNO{sub 3}/14.8M H{sub 3}PO{sub 4} solution. Addition of 0.001M Pd{sup 2+} reduces the CO to near 1% of the released carbon gases. To accomplish complete oxidation the solution temperature must be maintained above 130--150{degrees}C. Organic materials quantitatively destroyed include neoprene, cellulose, EDTA, TBP, tartaric acid, and nitromethane. The oxidation is usually complete in a few hours for soluble organic materials. The oxidation rate for non-aliphatic organic solids is moderately fast and surface area dependent. Polyethylene is quantitatively oxidized in 1.0M HNO{sub 3}/13.8M H{sub 3}PO{sub 4} solution while contained in pressure vessels heated with microwave energy. This is probably due to the high concentrations of NO{sub 2}{center_dot} obtained in the reaction environment.

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

    PubMed

    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.

  17. 40 CFR 721.6200 - Fatty acid polyamine condensate, phosphoric acid ester salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., phosphoric acid ester salts. 721.6200 Section 721.6200 Protection of Environment ENVIRONMENTAL PROTECTION... ester salts. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substances identified as fatty acid polyamine condensate, phosphate ester salts (PMNs P-90-1984 and P-90-1985...

  18. Effects of ultrasonic fields in the phosphoric acid process

    NASA Technical Reports Server (NTRS)

    Kowalska, E.; Mizera, J.; Jakobiec, H.

    1974-01-01

    A process of apatite decomposition with sulfuric acid was studied under the influence of ultrasound in the phosphoric acid production process. The studies were carried out with and without ultrasonic fields in the reaction mixture, which resembled the mixing ratio used in technical production processes. Ultrasound with a frequency of 20 kHz and an intensity of 1 W/sq cm was used in the studies. A very favorable ultrasonic effect upon the degree of apatite decomposition was observed. The ultrasonic field affects the shape of byproduct gypsum crystals. In the H3PO4 production process without ultrasound, the byproduct gypsum crystallizes as long, thin needles which cause problems in filtration. In the trials involving the application of wound, gypsum crystallized in the form of small platelets possessing a favorable ratio of length to width.

  19. Effects of ultrasonic fields in the phosphoric acid process

    NASA Technical Reports Server (NTRS)

    Kowalska, E.; Mizera, J.; Jakobiec, H.

    1974-01-01

    A process of apatite decomposition with sulfuric acid was studied under the influence of ultrasound in the phosphoric acid production process. The studies were carried out with and without ultrasonic fields in the reaction mixture, which resembled the mixing ratio used in technical production processes. Ultrasound with a frequency of 20 kHz and an intensity of 1 W/sq cm was used in the studies. A very favorable ultrasonic effect upon the degree of apatite decomposition was observed. The ultrasonic field affects the shape of byproduct gypsum crystals. In the H3PO4 production process without ultrasound, the byproduct gypsum crystallizes as long, thin needles which cause problems in filtration. In the trials involving the application of wound, gypsum crystallized in the form of small platelets possessing a favorable ratio of length to width.

  20. Structural changes of oil palm empty fruit bunch (OPEFB) after fungal and phosphoric acid pretreatment.

    PubMed

    Isroi; Ishola, Mofoluwake M; Millati, Ria; Syamsiah, Siti; Cahyanto, Muhammad N; Niklasson, Claes; Taherzadeh, Mohammad J

    2012-12-17

    Oil palm empty fruit bunch (OPEFB) was pretreated using white-rot fungus Pleurotus floridanus, phosphoric acid or their combination, and the results were evaluated based on the biomass components, and its structural and morphological changes. The carbohydrate losses after fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 7.89%, 35.65%, and 33.77%, respectively. The pretreatments changed the hydrogen bonds of cellulose and linkages between lignin and carbohydrate, which is associated with crystallinity of cellulose of OPEFB. Lateral Order Index (LOI) of OPEFB with no pretreatment, with fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 2.77, 1.42, 0.67, and 0.60, respectively. Phosphoric acid pretreatment showed morphological changes of OPEFB, indicated by the damage of fibre structure into smaller particle size. The fungal-, phosphoric acid-, and fungal followed by phosphoric acid pretreatments have improved the digestibility of OPEFB's cellulose by 4, 6.3, and 7.4 folds, respectively.

  1. 40 CFR 721.10140 - Phosphoric acid, tin (2+) salt (2:3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphoric acid, tin (2+) salt (2:3... Specific Chemical Substances § 721.10140 Phosphoric acid, tin (2+) salt (2:3). (a) Chemical substance and...+) salt (2:3) (PMN P-06-33, CAS No. 15578-32-2) is subject to reporting under this section for...

  2. 40 CFR 721.10140 - Phosphoric acid, tin (2+) salt (2:3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, tin (2+) salt (2:3... Specific Chemical Substances § 721.10140 Phosphoric acid, tin (2+) salt (2:3). (a) Chemical substance and...+) salt (2:3) (PMN P-06-33, CAS No. 15578-32-2) is subject to reporting under this section for...

  3. 40 CFR 721.10140 - Phosphoric acid, tin (2+) salt (2:3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid, tin (2+) salt (2:3... Specific Chemical Substances § 721.10140 Phosphoric acid, tin (2+) salt (2:3). (a) Chemical substance and...+) salt (2:3) (PMN P-06-33, CAS No. 15578-32-2) is subject to reporting under this section for...

  4. 40 CFR 721.10140 - Phosphoric acid, tin (2+) salt (2:3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid, tin (2+) salt (2:3... Specific Chemical Substances § 721.10140 Phosphoric acid, tin (2+) salt (2:3). (a) Chemical substance and...+) salt (2:3) (PMN P-06-33, CAS No. 15578-32-2) is subject to reporting under this section for...

  5. Evaluation of sodium bisulphate and phosphoric acid as urine acidifiers for cats.

    PubMed

    Spears, Julie K; Grieshop, Christine M; Fahey, G C

    2003-10-01

    Eighteen cats were used to compare the urine acidifying properties of sodium bisulphate to phosphoric acid. Acidifying agents were added at one of three concentrations (0.4, 0.6, or 0.8%, as-is basis). Cats were offered a commercial diet to determine basal urinary pH, and then again for a 1 week period between blocks 1 and 2. Cats were acclimated to the diets for 6 days, and urine samples were collected on day 7 at 0, 4, and 8 h postfeeding to obtain pre- and postprandial urinary pH. Intakes of diets containing sodium bisulphate tended (P < 0.07) to be lower than intakes of diets containing phosphoric acid. Cats consuming the 0.8% phosphoric acid diet had higher (P < 0.05) food intakes than cats consuming either the 0.4 or 0.6% phosphoric acid-containing diets. There was significant (P = 0.01) linear and quadratic response for food intake in cats consuming the sodium bisulphate-containing diet. Cats consuming the 0.4 and 0.8% phosphoric acid-containing diets tended (P = 0.07) to have higher water intakes than cats consuming the 0.6% phosphoric acid-containing diet. There were no differences (P > 0.05) in urine pH and specific gravity between cats fed the different acidifier types. Cats consuming the 0.6% phosphoric acid-containing diet tended (P = 0.07) to have a higher urine pH 8 h post-feeding than cats consuming the 0.4 and 0.8% phosphoric acid-containing diets. Urine pH was highest at 4 h post-feeding except for cats fed the 0.4% sodium bisulphate- and the 0.6% phosphoric acid-containing diets. No differences (P > 0.05) between acidifiers were found in faecal score or in faecal dry matter and organic matter concentrations. A quadratic response was detected in faecal score for cats consuming the phosphoric acid-containing diets. Cats consuming the 0.6% phosphoric acid diet tended (P = 0.06) to have a lower faecal score than cats consuming the 0.4 and 0.8% phosphoric acid diets. For faecal dry matter, a linear trend was detected in cats consuming the sodium

  6. SEM ANALYSIS OF THE ACID-ETCHED ENAMEL PATTERNS PROMOTED BY ACIDIC MONOMERS AND PHOSPHORIC ACIDS

    PubMed Central

    Shinohara, Mirela Sanae; de Oliveira, Marcelo Tavares; Hipólito, Vinícius Di; Giannin, Marcelo; de Goes, Mario Fernando

    2006-01-01

    Objective: Although self-etching bonding systems (SES) are indicated to prepare dental enamel for bonding, concerns have been expressed regarding their effectiveness. The aim of this study was to analyze the etching pattern (EP) of nine SES in comparison with 35% and 34% phosphoric acid etchants (FA) on intact (IN) and ground (GR) enamel surface. Materials and Methods: Twenty-two human third molars were sectioned in mesial-distal and buccal-lingual directions, and four dental fragments were obtained from each tooth. Half of the fragments were ground using 600-grit SiC paper and the other half remained intact. The fragments were randomly assigned into 22 groups, according to the texture of enamel surface (IN and GR) and the technique to etch the enamel (34% FA, 35% FA, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer and Xeno III). Conditioners were applied to IN and GR enamel surfaces, according to the manufacturer's instructions. Specimens etched with phosphoric acids were washed with water, while the surfaces treated with SES were submitted to alternate rinsing with alcohol and acetone. The specimens were dried, sputter-coated and examined under a scanning electron microscope. Results: For both IN and GR enamel surfaces, the EP of 34 and 35% FA was deeper and more homogeneous in comparison to EP of SES, except for Tyrian SPE. The acidic monomer action of self-etching systems was more effective on GR enamel. Conclusion: Most of the SES are less aggressive than phosphoric acid etchants and their etching effects were reduced on intact enamel surfaces. Uniterms: Dental acid etching; Dental enamel; Electron microscopy. PMID:19089243

  7. Theoretical study on the acidities of chiral phosphoric acids in dimethyl sulfoxide: hints for organocatalysis.

    PubMed

    Yang, Chen; Xue, Xiao-Song; Jin, Jia-Lu; Li, Xin; Cheng, Jin-Pei

    2013-07-19

    The pKa values of 41 chiral phosphoric acid-family catalysts in DMSO were predicted using the SMD/M06-2x/6-311++G(2df,2p)//B3LYP/6-31+G(d) method for the first time. The study showed that the calculated pKa's range from -4.23 to 6.16 for absolute pKa values and from -4.21 to 6.38 for relative pKa values. Excellent agreement between the calculated and experimental pKa's was achieved for the few available cases (to a precision of around 0.4 pKa unit), indicating that this strategy may be suitable for calculating highly accurate pKa's. A good linear correlation between the pKa's for 3 and 3' disubstituted phenyl BINOL phosphoric acids and the Hammett constants was obtained. The relationship between the acidities of phosphoric acid catalysts and their reaction activity and selectivity was also discussed. Knowledge of the pKa values of phosphoric acids should be of great value for the understanding of chiral Brønsted acid-catalyzed reactions and may aid in future catalyst design.

  8. 40 CFR 721.6100 - Phosphoric acid, C6-12-alkyl esters, compounds with 2-(dibutylamino) ethanol.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphoric acid, C6-12-alkyl esters... Significant New Uses for Specific Chemical Substances § 721.6100 Phosphoric acid, C6-12-alkyl esters... reporting. (1) The chemical substances identified as phosphoric acid, C6-12-alkyl esters, compounds with 2...

  9. 40 CFR 721.6100 - Phosphoric acid, C6-12-alkyl esters, compounds with 2-(dibutylamino) ethanol.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphoric acid, C6-12-alkyl esters... Significant New Uses for Specific Chemical Substances § 721.6100 Phosphoric acid, C6-12-alkyl esters... reporting. (1) The chemical substances identified as phosphoric acid, C6-12-alkyl esters, compounds with 2...

  10. Picosecond Pulse Radiolysis of Highly Concentrated Phosphoric Acid Solutions: Mechanism of Phosphate Radical Formation.

    PubMed

    Ma, Jun; Schmidhammer, Uli; Mostafavi, Mehran

    2015-06-18

    Eight solutions containing phosphoric acid with concentrations ranging from 2 mol L(-1) to neat acid have been studied by picosecond pulse radiolysis. The absorbance of the secondary radical H2PO4(•) formed within 7 ps of the electron pulse is observed using pulse-probe method in the visible. Kinetic analysis shows that the radicals of phosphoric acid are formed via two mechanisms: direct electron detachment and oxidation by the radical cation of water, H2O(•+). On the basis of molar extinction coefficient value of 1850 L mol(-1) cm(-1), at 15 ps the radiolytic yield of H2PO4(•) formation by direct energy absorption is 3.7 ± 0.1 × 10(-7) mol J(-1) in neat phosphoric acid. In highly concentrated phosphoric acid solutions, the total yield of phosphate radical at 15 ps exhibits an additional contribution that can be explained by electron transfer from phosphoric acid to H2O(•+). The efficiency of the electron transfer to this strongly oxidizing species in phosphoric acid solutions is lower compared with the one in sulfuric acid solutions. Two explanations are given to account for a relatively low efficiency of H2O(•+) scavenging in concentrated phosphoric acid solutions.

  11. Technology development for phosphoric acid fuel cell powerplant, phase 2

    NASA Technical Reports Server (NTRS)

    Christner, L.

    1981-01-01

    The development of materials, cell components, and reformers for on site integrated energy systems is described. Progress includes: (1) heat-treatment of 25 sq cm, 350 sq cm and 1200 sq cm cell test hardware was accomplished. Performance of fuel cells is improved by using this material; (2) electrochemical and chemical corrosion rates of heat-treated and as-molded graphite/phenolic resin composites in phosphoric acid were determined; (3) three cell, 5 in. x 15 in. stacks operated for up to 10,000 hours and 12 in. x 17 in. five cell stacks were tested for 5,000 hours; (4) a three cell 5 in. x 15 in. stack with 0.12 mg Pt/sq cm anodes and 0.25 mg Pt/sq cm cathodes was operated for 4,500 hours; and (5) an ERC proprietary high bubble pressure matrix, MAT-1, was tested for up to 10,000 hours.

  12. Transmission electron microscopic examination of phosphoric acid fuel cell components

    NASA Technical Reports Server (NTRS)

    Pebler, A.

    1986-01-01

    Transmission electron microscopy (TEM) was used to physically characterize tested and untested phosphoric acid fuel cell (PAFC) components. Those examined included carbon-supported platinum catalysts, carbon backing paper, and Teflon-bonded catalyst layers at various stages of fabrication and after testing in pressurized PAFC's. Applicability of electron diffraction and electron energy loss spectroscopy for identifying the various phases was explored. The discussion focuses on the morphology and size distribution of platinum, the morphology and structural aspects of Teflon in catalyst layers, and the structural evidence of carbon corrosion. Reference is made to other physical characterization techniques where appropriate. A qualitative model of the catalyst layer that emerged from the TEM studies is presented.

  13. Corrosion-resistant catalyst supports for phosphoric acid fuel cells

    SciTech Connect

    Kosek, J.A.; Cropley, C.C.; LaConti, A.B.

    1990-01-01

    High-surface-area carbon blacks such as Vulcan XC-72 (Cabot Corp.) and graphitized carbon blacks such as 2700{degree}C heat-treated Black Pearls 2000 (HTBP) (Cabot Corp.) have found widespread applications as catalyst supports in phosphoric acid fuel cells (PAFCs). However, due to the operating temperatures and pressures being utilized in PAFCs currently under development, the carbon-based cathode catalyst supports suffer from corrosion, which decreases the performance and life span of a PAFC stack. The feasibility of using alternative, low-cost, corrosion-resistant catalyst support (CRCS) materials as replacements for the cathode carbon support materials was investigated. The objectives of the program were to prepare high-surface-area alternative supports and to evaluate the physical characteristics and the electrochemical stability of these materials. The O{sub 2} reduction activity of the platinized CRCS materials was also evaluated. 2 refs., 3 figs.

  14. Preparation and characterization of cellulose regenerated from phosphoric acid.

    PubMed

    Jia, Xuejuan; Chen, Yingwen; Shi, Chong; Ye, Yangfan; Wang, Peng; Zeng, Xiaoxiong; Wu, Tao

    2013-12-18

    Native cellulose has a highly crystalline structure stabilized by a strong intra- and intermolecular hydrogen-bond network. It is usually not considered as a good gelling material and emulsion stabilizer due to its insolubility in water. Chemical modification is generally necessary to obtain cellulose derivatives for these applications. In this study, we have shown that, by simply disrupting the hydrogen-bond network of cellulose with phosphoric acid treatment, the regenerated cellulose can be a good gelling material and emulsion stabilizer. Microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analysis have confirmed that the regenerated cellulose is primarily amorphous with low crystallinity in the structure of cellulose II. Stable aqueous suspensions and opaque gels that resist flowing can be obtained with the regenerated cellulose at concentrations higher than 0.6% and 1.6%, respectively. Moreover, it can effectively stabilize oil-in-water emulsions at concentrations less than 1% by a mechanism that combines network and Pickering stabilization.

  15. Organometallic catalysts for primary phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    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. Organometallic catalysts for primary phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Walsh, Fraser

    1987-03-01

    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.

  17. Addition of Grape Seed Extract Renders Phosphoric Acid a Collagen-stabilizing Etchant.

    PubMed

    Liu, Y; Dusevich, V; Wang, Y

    2014-08-01

    Previous studies found that grape seed extract (GSE), which is rich in proanthocyanidins, could protect demineralized dentin collagen from collagenolytic activities following clinically relevant treatment. Because of proanthocyanidin's adverse interference to resin polymerization, it was believed that GSE should be applied and then rinsed off in a separate step, which in effect increases the complexity of the bonding procedure. The present study aimed to investigate the feasibility of combining GSE treatment with phosphoric acid etching to address the issue. It is also the first attempt to formulate collagen-cross-linking dental etchants. Based on Fourier-transformed infrared spectroscopy and digestion assay, it was established that in the presence of 20% to 5% phosphoric acid, 30 sec of GSE treatment rendered demineralized dentin collagen inert to bacterial collagenase digestion. Based on this positive result, the simultaneous dentin etching and collagen protecting of GSE-containing phosphoric acid was evaluated on the premise of a 30-second etching time. According to micro-Raman spectroscopy, the formulation containing 20% phosphoric acid was found to lead to overetching. Based on scanning and transmission electronic microscopy, this same formulation exhibited unsynchronized phosphoric acid and GSE penetration. Therefore, addition of GSE did render phosphoric acid a collagen-stabilizing etchant, but the preferable phosphoric acid concentration should be <20%. © International & American Associations for Dental Research.

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

    PubMed

    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

  19. Method for separating mono- and di-octylphenyl phosphoric acid esters

    DOEpatents

    Arnold, Jr., Wesley D.

    1977-01-01

    A method for separating mono-octylphenyl phosphoric acid ester and di-octylphenyl phosphoric acid ester from a mixture thereof comprises reacting the ester mixture with a source of lithium or sodium ions to form a mixture of the phosphate salts; contacting the salt mixture with an organic solvent which causes the dioctylphenyl phosphate salt to be dissolved in the organic solvent phase and the mono-octylphenyl phosphate salt to exist in a solid phase; separating the phases; recovering the phosphate salts from their respective phases; and acidifying the recovered salts to form the original phosphoric acid esters.

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

    PubMed

    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.

  1. Conversion of waste cellulose to ethanol. Phase II. Reaction kinetics with phosphoric acid

    SciTech Connect

    Moeller, M.B.; Isbell, R.E.

    1982-05-01

    Waste cellulosic material can be hydrolyzed in dilute acid solution to produce fermentable sugars which can then be converted into ethanol. A laboratory investigation was made of the feasibility of using phosphoric acid as the hydrolysis catalyst. The hydrolysis reaction with phosphoric acid solutions was compared with the reaction employing the more conventional dilute sulfuric acid catalyst. The purpose of this research was to examine the hydrolysis step in a proposed process for the conversion of cellulose (from wood, newspapers, municipal solid waste, or other sources) into ethanol - by which a potentially valuable co-product, DICAL (dicalcium phosphate), might be made and sold with or without the lignin content as a fertilizer. The pertinent reaction kinetics for the acid catalyzed production of glucose from cellulose consists of consecutive, pseudo-first order reactions. The first reaction forms glucose by hydrolyzing the cellulose polymer and a subsequent reaction decomposes the glucose. The maximum theoretical yield depends on the ratio of the rate constants for these two reactions. The rate constants of both reactions were measured in a series of experiments studying temperature and concentration effects. The results suggest that the glucose decomposition reaction is similar with the two acids but that the cellulose hydrolysis reaction mechanism with phosphoric acid may be different than with sulfuric acid. The studies show phosphoric acid is unpromising and much inferior to sulfuric acid as the catalytic agent. Under the conditions studied, 0.8 wt % sulfuric acid gives a greater yield of glucose than 8.0 wt % phosphoric acid.

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

    SciTech Connect

    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.

  3. Chiral phosphoric acid catalyzed enantioselective 1,3-dipolar cycloaddition reaction of azlactones.

    PubMed

    Zhang, Zhenhua; Sun, Wangsheng; Zhu, Gongming; Yang, Junxian; Zhang, Ming; Hong, Liang; Wang, Rui

    2016-01-25

    The first chiral phosphoric acid catalyzed highly diastereo- and enantioselective 1,3-dipolar cycloaddition reaction of azlactones and methyleneindolinones was disclosed. By using a BINOL-derived chiral phosphoric acid as the catalyst, azlactones were activated as chiral anti N-protonated 1,3-dipoles to react with methyleneindolinones to yield biologically important 3,3'-pyrrolidonyl spirooxindole scaffolds in high yields, with good-to-excellent diastereo- and enantioselectivity.

  4. Dry compliant seal for phosphoric acid fuel cell

    DOEpatents

    Granata, Jr., Samuel J.; Woodle, Boyd M.

    1990-01-01

    A dry compliant overlapping seal for a phosphoric acid fuel cell preformed f non-compliant Teflon to make an anode seal frame that encircles an anode assembly, a cathode seal frame that encircles a cathode assembly and a compliant seal frame made of expanded Teflon, generally encircling a matrix assembly. Each frame has a thickness selected to accommodate various tolerances of the fuel cell elements and are either bonded to one of the other frames or to a bipolar or end plate. One of the non-compliant frames is wider than the other frames forming an overlap of the matrix over the wider seal frame, which cooperates with electrolyte permeating the matrix to form a wet seal within the fuel cell that prevents process gases from intermixing at the periphery of the fuel cell and a dry seal surrounding the cell to keep electrolyte from the periphery thereof. The frames may be made in one piece, in L-shaped portions or in strips and have an outer perimeter which registers with the outer perimeter of bipolar or end plates to form surfaces upon which flanges of pan shaped, gas manifolds can be sealed.

  5. Combined cycle phosphoric acid fuel cell electric power system

    SciTech Connect

    Mollot, D.J.; Micheli, P.L.

    1995-12-31

    By arranging two or more electric power generation cycles in series, combined cycle systems are able to produce electric power more efficiently than conventional single cycle plants. The high fuel to electricity conversion efficiency results in lower plant operating costs, better environmental performance, and in some cases even lower capital costs. Despite these advantages, combined cycle systems for the 1 - 10 megawatt (MW) industrial market are rare. This paper presents a low noise, low (oxides of nitrogen) NOx, combined cycle alternative for the small industrial user. By combining a commercially available phosphoric acid fuel cell (PAFC) with a low-temperature Rankine cycle (similar to those used in geothermal applications), electric conversion efficiencies between 45 and 47 percent are predicted. While the simple cycle PAFC is competitive on a cost of energy basis with gas turbines and diesel generators in the 1 to 2 MW market, the combined cycle PAFC is competitive, on a cost of energy basis, with simple cycle diesel generators in the 4 to 25 MW market. In addition, the efficiency and low-temperature operation of the combined cycle PAFC results in a significant reduction in carbon dioxide emissions with NO{sub x} concentration on the order of 1 parts per million (per weight) (ppmw).

  6. Development of advanced kocite electrocatalysts for phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Welsh, L. S.; Leyerle, R. W.; Scarlata, D. S.; Vanek, M. A.

    1981-01-01

    These improved electrocatalysts should demonstrate a larger initial catalytic metal surface area, and a better catalytic metal surface area retention during fuel cell operation than present state-of-the-art phosphoric acid electrocatalysts. Kocite electrocatalysts impregnated with platinum and platinum-vanadium alloys were tested. The Kocite electrocatalysts were aged in electrodes potentiostated in H3PO4 half cells, and were then analyzed for catalytic metals surface area retention. Compared with the state-of-the-art platinum electrocatalysts, as represented by a standard Kocite electrocatalyst, the Kocite electrocatalysts impregnated by the techniques used in this study have a better initial platinum surface area. This initial surface area difference appeared to be maintained when the catalysts are aged at 700 mV, but was not maintained when the catalysts were aged at 800 mV. Variations of the alumina substrate and of the post-treatment of the leached Kocite catalyst support did not produce any catalysts with better platinum surface area retention than the standard catalyst. Alloying of vanadium with the platinum did produce Kocite electrocatalysts which maintained their alloy surface area better than the standard catalyst maintained its platinum surface area.

  7. Intelligent machine learning analysis for phosphoric acid fuel cell operations

    SciTech Connect

    Hoyt, W.; Foote, J.P.; Murphy, R.W.; Chen, F.C.

    1998-07-01

    Several fuel cell types are available and are in various stages of technology development. The complex nature of the balance of plant and fuel cell interface poses many technical challenges to achieve proper system control under commercial operating conditions. Real-time predictive diagnostic computer systems based on advanced intelligent machine learning technologies offer a means to facilitate the detection, understanding, and control of fuel cell subsystems to avoid system instabilities and failures that can result in costly plant shutdowns. The objectives reported herein are the development of physical and empirical computer models for application and testing of predictive control strategies based on intelligent machine learning techniques for fuel cells. A physical/empirical model was built and validated using available operating data from commercial fuel cells. Neural networks were then used to build an empirical model from the original physical/empirical model. Using the neural network model, a predictive, feedforward strategy was developed to control the fuel flow for a phosphoric acid fuel cell physical/empirical model. The predictive control strategy was compared to traditional proportional integral derivative control schemes.

  8. Phosphorous acid residues in apples after foliar fertilization: results of field trials.

    PubMed

    Malusà, E; Tosi, L

    2005-06-01

    The levels of phosphorous acid residues in apples after foliar fertilization with P fertilizers and after treatment with a phosphonate fungicide (Fosetyl-Al) were determined and compared. Two field trials and a glasshouse experiment, using different genotypes and plants of different age, were carried out and monitored over a three-year period. Phosphorous acid residues were found in apples after application of foliar P fertilizers. Concentrations of the residues ranged between 0.02 and 14 mg kg(-1) depending on the phosphorous acid content in the fertilizer used and the plant size and yield. The treatments induced an accumulation of the residue in the course of the experiments, which in some cases reached a level exceeding the maximum limit set by EU legislation. Residues were also detected in other plant organs, i.e., roots and buds. Plants treated with Fosetyl-Al contained phosphorous acid residues in their fruits and buds two years after the suspension of the treatment, suggesting a long-term persistence of the substance in plant storage organs. A second experiment, involving treatment of trees with seven foliar fertilizers of different composition, also induced accumulation of phosphorous acid residues in fruits. It is concluded that a wide array of foliar products containing phosphorous acid, even as a minor component, could mimic the residue effect of phosphonate fungicide treatments.

  9. Diluted phosphoric acid pretreatment for production of fermentable sugars in a sugarcane-based biorefinery.

    PubMed

    de Vasconcelos, Solange Maria; Santos, Andrelina Maria Pinheiro; Rocha, George Jackson Moraes; Souto-Maior, Ana Maria

    2013-05-01

    The influence of time (8-24 min), temperature (144-186 °C) and phosphoric acid concentration (0.05-0.20%, w/v) on the pretreatment of sugarcane bagasse in a 20 L batch rotary reactor was investigated. The efficiency of the pretreatment was verified by chemical characterization of the solid fraction of the pretreated bagasse and the conversion of cellulose to glucose by enzymatic hydrolysis. Models representing the percentage of cellulose, hemicelluloses, lignin, solubilized hemicellulose and the enzymatic conversion of cellulose to glucose were predictive and significant. Phosphoric acid concentration of 0.20% at temperature of 186 °C, during 8 and 24 min, was shown to be very effective in solubilizing hemicellulose from sugarcane bagasse, reaching solubilization of 96% and 98%, respectively. Relatively low amounts of inhibitors were produced, and the phosphoric acid remaining in the hemicellulosic hydrolysate is at adequate levels for supplying phosphorous requirement during subsequent fermentation.

  10. Method of recovering uranium from wet process phosphoric acid with enhanced content of uranium

    SciTech Connect

    Yoshikawa, S.; Nakamura, R.

    1984-01-24

    In preparing wet process phosphoric acid by decomposing a phosphate rock containing uranium with sulfuric acid and phosphoric acid on condition that hemihydrate gypsum is formed in an acid solution either at the stage of decomposing the phosphate rock or subsequently, uranium contained in the phosphate rock can almost entirely be retained in the obtained phosphoric acid solution by forming the hemihydrate gypsum in the presence of an oxidizing agent, such as a soluble chlorate, hydrogen peroxide or oxygen gas, in the acid solution in a quantity sufficient to render the entire uranium dissolved in the acid solution hexavalent because hemihydrate gypsum adsorbs almost exclusively tetravalent ions of uranium. The uranium is then recovered.

  11. Evaluation of Mineral Content and Photon Interaction Parameters of Dental Enamel After Phosphoric Acid and Er:YAG Laser Treatment.

    PubMed

    Simsek, Huseyin; Gurbuz, Taskın; Buyuk, Suleyman Kutalmış; Ozdemir, Yuksel

    2017-05-01

    The purpose of this study was to evaluate the effects of laser and acid etching on the mineral content and photon interaction parameters of dental enamel in human teeth. The composition of dental enamel may vary, especially at the surface, depending on the reactions that occur during dental treatment. Forty maxillary premolars were divided randomly into 2 groups of 20 teeth. In the first group, half of teeth crowns were etched by using 37% phosphoric acid; in the second group, half of teeth crowns were etched by using an erbium:yttrium-aluminum-garnet (Er:YAG) laser. The remaining half crowns in each group were used as untreated controls. We characterized the calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), and potassium (K) contents in each specimen by using wavelength dispersive X-ray fluorescence spectrometry. The total atomic cross-section ([Formula: see text]), effective atomic number ([Formula: see text]), and electron density (Ne) of the tooth samples were determined at photon energies of 22.1, 25, 59.5, and 88 keV by using a narrow beam transmission method. Data were analyzed statistically by using the Mann-Whitney U test. The mineral contents after Er:YAG laser and phosphoric acid etching did not differ significantly (p > 0.05), and no significant variation in [Formula: see text], [Formula: see text], or Ne was observed. Therefore, we conclude that the Er:YAG laser and phosphoric acid systems used in this study did not affect mineral composition or photon interaction parameters of dental enamel.

  12. Evolution of the graphite surface in phosphoric acid: an AFM and Raman study

    PubMed Central

    Brambilla, Luigi; Bussetti, Gianlorenzo; Tommasini, Matteo; Li Bassi, Andrea; Casari, Carlo Spartaco; Passoni, Matteo; Ciccacci, Franco; Duò, Lamberto; Castiglioni, Chiara

    2016-01-01

    Phosphoric acid is an inorganic acid used for producing graphene sheets by delaminating graphite in (electro-)chemical baths. The observed phenomenology during the electrochemical treatment in phosphoric acid solution is partially different from other acidic solutions, such as sulfuric and perchloric acid solutions, where the graphite surface mainly forms blisters. In fact, the graphite surface is covered by a thin layer of modified (oxidized) material that can be observed when an electrochemical potential is swept in the anodic current regime. We characterize this particular surface evolution by means of a combined electrochemical, atomic force microscopy and Raman spectroscopy investigation. PMID:28144537

  13. Potassium

    MedlinePlus

    ... the potassium you need. However, certain diseases (e.g., kidney disease and gastrointestinal disease with vomiting and ... substitute and to eat potassium-rich foods (e.g., bananas, prunes, raisins, and milk).

  14. 40 CFR 422.50 - Applicability; description of the defluorinated phosphoric acid subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false Applicability; description of the defluorinated phosphoric acid subcategory. 422.50 Section 422.50 Protection of Environment ENVIRONMENTAL... processing acids such as vacuum and air stripping. The acid is concentrated up to 70-73% P2 O5 in...

  15. Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants

    PubMed Central

    PRADO, Maíra; da SILVA, Emmanuel João Nogueira Leal; DUQUE, Thais Mageste; ZAIA, Alexandre Augusto; FERRAZ, Caio Cezar Randi; de ALMEIDA, José Flávio Affonso; GOMES, Brenda Paula Figueiredo de Almeida

    2015-01-01

    Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. Objectives : The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. Material and Methods : The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel), and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Results : Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution), whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Conclusion : Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution). PMID:26018307

  16. Recovery of uranium from phosphoric acid solutions using chelating ion-exchange resins

    SciTech Connect

    Kabay, N.; Demircioglu, M.; Yayh, S.; Guenay, E.; Yueksel, M.; Saglam, M.; Streat, M.

    1998-05-01

    In fertilizer manufacture, calcium phosphate in phosphate rock is rendered soluble by sulfuric acid attack. The phosphoric acid obtained in this way usually contains 26%--28% P{sub 2}O{sub 5}. Several novel processes have been developed for the recovery of uranium from wet-process phosphoric acid. Experimental measurements have been made on the batch extraction of uranium from phosphoric acid solutions using various chelating ion-exchange resins (RSPO, Diaion-CRP200, Diphonix, Purolite S940, Duolite ES467, and Lewatit OC 1060) and a solvent containing ion-exchange resins (Actinide-CU). The kinetic performance of ion-exchange resins was compared, and the effect of Fe(II) and Ca(II) ions on the sorption and elution performance has also been examined. The results showed that the resin Actinide-CU containing a diphosphonate extractant was very effective for removing uranium from phosphoric acid solution. However, the elution performance of this resin with both acid and carbonate eluants was poor. It is concluded that the chelating resins Diphonix, Duolite ES467, Lewatit OC 1060, and Purolite S940 give reasonable sorption of uranium in the presence of Fe(II) ions in batch sorption trials. The desorption of uranium has been performed quantitatively using carbonate eluants. Purolite S940 was used in small-scale column extractions of uranium from phosphoric acid solutions, and promising loading/elution profiles were obtained.

  17. Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants.

    PubMed

    Prado, Maíra; Silva, Emmanuel João Nogueira Leal da; Duque, Thais Mageste; Zaia, Alexandre Augusto; Ferraz, Caio Cezar Randi; Almeida, José Flávio Affonso de; Gomes, Brenda Paula Figueiredo de Almeida

    2015-01-01

    Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel), and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution), whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution).

  18. Production of monosaccharides from napier grass by hydrothermal process with phosphoric acid.

    PubMed

    Takata, Eri; Tsutsumi, Ken; Tsutsumi, Yuji; Tabata, Kenji

    2013-09-01

    The production of monosaccharides from napier grass was investigated in the presence of acid catalysts using the hydrothermal process. When the napier grass was treated with 3 wt.% phosphoric acid at 160°C for 15min, the xylose yield reached 10.3 wt.%, corresponding to 72.0% of the xylan in it, whereas glucose was hardly obtained. A combined process was then conducted using an 85 wt.% phosphoric acid treatment at 60 °C for 1h followed by a hydrothermal treatment with 3 wt.% phosphoric acid. In the initial treatment with concentrated phosphoric acid the most of xylan was hydrolyzed to xylose, and the crystalline cellulose was converted to its amorphous form. The hydrolysis of cellulose to glucose was significantly enhanced during the following hydrothermal process with 3 wt.% phosphoric acid at 200 °C for 8 min. Consequently, 77.2% yield of xylose and 50.0% yield of glucose were obtained from the combined process.

  19. Removal of free fatty acid in Azadirachta indica (Neem) seed oil using phosphoric acid modified mordenite for biodiesel production.

    PubMed

    SathyaSelvabala, Vasanthakumar; Varathachary, Thiruvengadaravi Kadathur; Selvaraj, Dinesh Kirupha; Ponnusamy, Vijayalakshmi; Subramanian, Sivanesan

    2010-08-01

    In this study free fatty acids present in Azadirachta indica (Neem) oil were esterified with our synthesized phosphoric acid modified catalyst. During the esterification, the acid value was reduced from 24.4 to 1.8 mg KOH/g oil. Synthesized catalyst was characterized by NH(3) TPD, XRD, SEM, FTIR and TGA analysis. During phosphoric acid modification hydrophobic character and weak acid sites of the mordenite were increased, which lead to better esterification when compared to H-mordenite. A kinetic study demonstrates that the esterification reaction followed pseudo-first order kinetics. Thermodynamic studies were also done based on the Arrhenius model. (c) 2010 Elsevier Ltd. All rights reserved.

  20. Acid-base and potassium disorders in liver disease.

    PubMed

    Ahya, Shubhada N; José Soler, Maria; Levitsky, Josh; Batlle, Daniel

    2006-11-01

    Acid-base and potassium disorders occur frequently in the setting of liver disease. As the liver's metabolic function worsens, particularly in the setting of renal dysfunction, hemodynamic compromise, and hepatic encephalopathy, acid-base disorders ensue. The most common acid-base disorder is respiratory alkalosis. Metabolic acidosis alone or in combination with respiratory alkalosis also is common. Acid-base disorders in patients with liver disease are complex. The urine anion gap may help to distinguish between chronic respiratory alkalosis and hyperchloremic metabolic acidosis when a blood gas is not available. A negative urine anion gap helps to rule out chronic respiratory alkalosis. In this disorder a positive urine anion gap is expected owing to suppressed urinary acidification. Distal renal tubular acidosis occurs in autoimmune liver disease such as primary biliary cirrhosis, but often is a functional defect from impaired distal sodium delivery. Potassium disorders are often the result of the therapies used to treat advanced liver disease.

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

    NASA Astrophysics Data System (ADS)

    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. Spatial variability of soil available phosphorous and potassium at three different soils located in Pannonian Croatia

    NASA Astrophysics Data System (ADS)

    Bogunović, Igor; Pereira, Paulo; Đurđević, Boris

    2017-04-01

    Information on spatial distribution of soil nutrients in agroecosystems is critical for improving productivity and reducing environmental pressures in intensive farmed soils. In this context, spatial prediction of soil properties should be accurate. In this study we analyse 704 data of soil available phosphorus (AP) and potassium (AK); the data derive from soil samples collected across three arable fields in Baranja region (Croatia) in correspondence of different soil types: Cambisols (169 samples), Chernozems (131 samples) and Gleysoils (404 samples). The samples are collected in a regular sampling grid (distance 225 x 225 m). Several geostatistical techniques (Inverse Distance to a Weight (IDW) with the power of 1, 2 and 3; Radial Basis Functions (RBF) - Inverse Multiquadratic (IMT), Multiquadratic (MTQ), Completely Regularized Spline (CRS), Spline with Tension (SPT) and Thin Plate Spline (TPS); and Local Polynomial (LP) with the power of 1 and 2; two geostatistical techniques -Ordinary Kriging - OK and Simple Kriging - SK) were tested in order to evaluate the most accurate spatial variability maps using criteria of lowest RMSE during cross validation technique. Soil parameters varied considerably throughout the studied fields and their coefficient of variations ranged from 31.4% to 37.7% and from 19.3% to 27.1% for soil AP and AK, respectively. The experimental variograms indicate a moderate spatial dependence for AP and strong spatial dependence for all three locations. The best spatial predictor for AP at Chernozem field was Simple kriging (RMSE=61.711), and for AK inverse multiquadratic (RMSE=44.689). The least accurate technique was Thin plate spline (AP) and Inverse distance to a weight with a power of 1 (AK). Radial basis function models (Spline with Tension for AP at Gleysoil and Cambisol and Completely Regularized Spline for AK at Gleysol) were the best predictors, while Thin Plate Spline models were the least accurate in all three cases. The best

  3. Performance of phosphoric acid activated montmorillonite as buffer materials for radioactive waste repository.

    PubMed

    Wang, Tsing-Hai; Liu, Tsung-Ying; Wu, Ding-Chiang; Li, Ming-Hsu; Chen, Jiann-Ruey; Teng, Shi-Ping

    2010-01-15

    In this study, the performance of phosphoric acid activated montmorillonite (PAmmt) was evaluated by cesium ions adsorption experiments. The PAmmt samples were obtained by activating with 1, 3 and 5 mol L(-1) of phosphoric acid, respectively under reflux for 3, 12, and 24h. Experimental results demonstrated that the treatment of raw K-10 montmorillonite with phosphoric acid increased the materials' affinity for Cs uptake and no significant amount of suspension solids were produced. A relatively insignificant variation in the CEC value was observed. Furthermore, PAmmt also showed high adsorption selectivity toward Cs ions. The improved sorptive properties were mainly related to the increased surface area and the relatively higher surface charge density. Increased specific surface area was the resulted from partial decomposition of lamellar structure of mmt; while the higher surface charge density was caused by the protonation of octahedral Al-OH sites during the acid activation. Generally speaking, stronger acid concentration and longer activation times would produce relatively more decomposed PAmmt particles. However, as the activation exceeds 3h, the precipitation of Si(4+) would passivate PAmmt against further acid attacks. Based upon our results, acid activation by phosphoric acid could produce PAmmt samples with high sorption capacity and selectivity, and good structural integrity, which are beneficial to be used at radioactive waste repository.

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

    PubMed

    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. 21 CFR 172.725 - Gibberellic acid and its potassium salt.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Gibberellic acid and its potassium salt. 172.725... HUMAN CONSUMPTION Other Specific Usage Additives § 172.725 Gibberellic acid and its potassium salt. The food additives gibberellic acid and its potassium salt may be used in the malting of barley in...

  6. 21 CFR 172.725 - Gibberellic acid and its potassium salt.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Gibberellic acid and its potassium salt. 172.725... HUMAN CONSUMPTION Other Specific Usage Additives § 172.725 Gibberellic acid and its potassium salt. The food additives gibberellic acid and its potassium salt may be used in the malting of barley in...

  7. 21 CFR 172.725 - Gibberellic acid and its potassium salt.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Gibberellic acid and its potassium salt. 172.725... HUMAN CONSUMPTION Other Specific Usage Additives § 172.725 Gibberellic acid and its potassium salt. The food additives gibberellic acid and its potassium salt may be used in the malting of barley in...

  8. 21 CFR 172.725 - Gibberellic acid and its potassium salt.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Gibberellic acid and its potassium salt. 172.725... HUMAN CONSUMPTION Other Specific Usage Additives § 172.725 Gibberellic acid and its potassium salt. The food additives gibberellic acid and its potassium salt may be used in the malting of barley in...

  9. 21 CFR 172.725 - Gibberellic acid and its potassium salt.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Gibberellic acid and its potassium salt. 172.725... Additives § 172.725 Gibberellic acid and its potassium salt. The food additives gibberellic acid and its potassium salt may be used in the malting of barley in accordance with the following prescribed...

  10. The effect of proanthocyanidin-containing 10% phosphoric acid on bonding properties and MMP inhibition.

    PubMed

    Hass, Viviane; Luque-Martinez, Issis; Muñoz, Miguel Angel; Reyes, Mario Felipe Gutierrez; Abuna, Gabriel; Sinhoreti, Mario Alexandre Coelho; Liu, Alex Yi; Loguercio, Alessandro D; Wang, Yong; Reis, Alessandra

    2016-03-01

    This study evaluated the effect of etching using 2% proanthocynidin-containing 10% phosphoric acid 2% PA/10% PhA vs. 35% phosphoric acid 35% PhA on immediate (IM) and 6-months (6M) resin-enamel microshear bond strength (μSBS), resin-dentin microtensile bond strength (μTBS), nanoleakage (NL) and as well as in situ MMP inhibition potential. The dentin surface of human were exposed and then etched using 35% phosphoric acid for 15s or 2% PA/10% phosphoric acid for 30s. After rinsing with water, the dentin was bonded with Single Bond Plus (3M ESPE) and composite build-ups were constructed, followed by polymerization. The teeth were sectioned and the bonds were testing for microtensile bond strength (μTBS) and by SEM for NL analysis at IM and 6M. For MMP activity, resin-dentin slices were prepared for in situ zymography, and analyzed under confocal microscopy. For μSBS, others teeth had flattened enamel surfaces etched according the experimental groups and prepared to microshear procedure. The specimens were tested IM and after 6M by microshear bond strength. The data were submitted to two-way repeated measures ANOVA and Tukey's test (α=0.05). Acid-etching using the 2% PA/10% phosphoric acid did not lower the μTBS in IM (p>0.05) compared to the control 35% phosphoric acid group. However, after 6M, only the 2% PA/10% PhA etched dentin had remained stable the resin-dentin bond strength (p<0.05). Bonds made with 35% PhA showed significant increase in NL% after 6M (p<0.05). Dentin bonds made with 2% PA/10% phosphoric acid showed no increase in NL% after 6 months. The MMP activity within the resin-dentin interface was almost completely reduced after 2% PA/10% PhA etching, while the 35% PhA exhibited intense MMP activity. For μSBS, the type of etchant and the storage period did not affect the resin-enamel bond strengths (p>0.05). Ten percent phosphoric acid containing 2% PA can produce stable resin-dentin and enamel-resin interfaces, without requiring additional steps

  11. Influence of phosphoric acid pretreatment on self-etching bond strengths.

    PubMed

    Erhardt, Maria Carolina Guilherme; Cavalcante, Larissa Maria Assad; Pimenta, Luiz André Freire

    2004-01-01

    The purpose of this investigation was to evaluate the influence of phosphoric acid pretreatment on shear bond strength of two self-etching bonding systems to enamel and dentin. Forty-eight extracted third human molar teeth were mounted, embedded into polystyrene resin, polished with 600-grit aluminum oxide papers, and randomly divided into four groups (n = 12): group 1-Clearfil Liner Bond 2V (Kuraray Co. Ltd., Osaka, Japan); group 2-One Up Bond F (Tokuyama Corp., Tokyo, Japan); group 3-phosphoric acid (Condicionador Dental Gel, Dentsply Ind. Com. LTDA, Rio de Janeiro, Brazil) and Clearfil Liner Bond 2V; group 4-phosphoric acid and One Up Bond F. In groups 3 and 4 the substrate was pre-etched for 15 seconds with 37% phosphoric acid, rinsed, and dried with an air stream. In all groups adhesive systems were applied according to manufacturers' instructions and light cured; then a restorative composite resin (TPH Spectrum, Dentsply Ind. Com. LTDA) was placed in a polytef matrix and cured. The specimens were stored in humidity for 7 days at 37 degrees C. The shear bond strength test was performed in a universal test machine with a crosshead speed of 0.5 mm/min. All procedures were repeated for the dentin evaluation. Mean values were analyzed with two-way analysis of variance and Duncan tests (p < .05). The values obtained are listed in decreasing order: enamel-group 3 = 24.6 MPa, group 4 = 23.6 MPa, group 1 = 19.2 MPa, group 2 = 8.5 MPa; dentin-group 1 = 17.2 MPa, group 2 = 16.1 MPa, group 4 = 13.1 MPa, group 3 = 11.3 MPa. Under the conditions of this study, enamel etching with 37% phosphoric acid provided statistically significant higher shear bond strength values, regardless of the adhesive system. However, in dentin, for Clearfil Liner Bond 2V, phosphoric acid pretreatment negatively affected bond strength values. The use of self-etching systems in composite-to-enamel bonding restorative techniques still needs improvement when compared with the high bond strengths

  12. Synthesis of hierarchical SAPO-11 using phosphoric acid-treated aluminosilicate zeolite as precursor

    NASA Astrophysics Data System (ADS)

    Yang, Zhichao; Liu, Yunqi; Liu, Chenguang

    2017-08-01

    Hierarchical SAPO-11 was synthesized using phosphoric acid-treated alum inosilicate zeolite as precursor without additional mesoscale templates. The sample was characterized by XRD, nitrogen adsorption-desorption, SEM, TEM, and MAS NMR. The results showed that the alum inosilicate zeolite was decomposed and transformed into hierarchical SAPO-11 after the treatment of phosphoric acid and hydrothermal crystallization. The obtained sample exhibited irregular aggregation of small crystals with rough surface and mesoporous structure. The formation mechanism of the mesoporous in this process was proposed based on analysis results.

  13. Implant decontamination with phosphoric acid during surgical peri-implantitis treatment: a RCT.

    PubMed

    Hentenaar, Diederik F M; De Waal, Yvonne C M; Strooker, Hans; Meijer, Henny J A; Van Winkelhoff, Arie-Jan; Raghoebar, Gerry M

    2017-12-01

    Peri-implantitis is known as an infectious disease that affects the peri-implant soft and hard tissue. Today, scientific literature provides very little evidence for an effective intervention protocol for treatment of peri-implantitis. The aim of the present randomized controlled trial is to evaluate the microbiological and clinical effectiveness of phosphoric acid as a decontaminating agent of the implant surface during surgical peri-implantitis treatment. Peri-implantitis lesions were treated with resective surgical treatment aimed at peri-implant granulation tissue removal, bone recontouring, and pocket elimination. Fifty-three implant surfaces in 28 patients were mechanically cleaned and treated with either 35% phosphoric etching gel (test group) or sterile saline (control group). Microbiological samples were obtained during surgery; clinical parameters were recorded at baseline and at 3 months after treatment. Data were analyzed using multi-variable linear regression analysis and multilevel statistics. Significant immediate reductions in total anaerobic bacterial counts on the implant surface were found in both groups. Immediate reduction was greater when phosphoric acid was used. The difference in log-transformed mean anaerobic counts between both procedures was not statistical significant (p = 0.108), but there were significantly less culture-positive implants after the decontamination procedure in the phosphoric acid group (p = 0.042). At 3 months post-surgery, 75% of the implants in the control group and 63.3% of the implants in the test group showed disease resolution. However, no significant differences in clinical and microbiological outcomes between both groups were found. The application of 35% phosphoric acid after mechanical debridement is superior to mechanical debridement combined with sterile saline rinsing for decontamination of the implant surface during surgical peri-implantitis treatment. However, phosphoric acid as implant surface

  14. Optimizing ethanol and methane production from steam-pretreated, phosphoric acid-impregnated corn stover.

    PubMed

    Bondesson, Pia-Maria; Dupuy, Aurélie; Galbe, Mats; Zacchi, Guido

    2015-02-01

    Pretreatment is of vital importance in the production of ethanol and methane from agricultural residues. In this study, the effects of steam pretreatment with phosphoric acid on enzymatic hydrolysis (EH), simultaneous saccharification and fermentation (SSF), anaerobic digestion (AD) and the total energy output at three different temperatures were investigated. The effect of separating the solids for SSF and the liquid for AD was also studied and compared with using the whole slurry first in SSF and then in AD. Furthermore, the phosphoric acid was compared to previous studies using sulphuric acid or no catalyst. Using phosphoric acid resulted in higher yields than when no catalyst was used. However, compared with sulphuric acid, an improved yield was only seen with phosphoric acid in the case of EH. The higher pretreatment temperatures (200 and 210 °C) resulted in the highest yields after EH and SSF, while the highest methane yield was obtained with the lower pretreatment temperature (190 °C). The highest yield in terms of total energy recovery (78 %) was obtained after pretreatment at 190 °C, but a pretreatment temperature of 200 °C is, however, the best alternative since fewer steps are required (whole slurry in SSF and then in AD) and high product yields were obtained (76 %).

  15. Influence of phosphoric acid on the electrochemistry of lead electrodes in sulfuric acid electrolyte containing antimony

    NASA Astrophysics Data System (ADS)

    Venugopalan, S.

    The influence of phosphoric acid (0 to 40 g 1 -1) on the Pb/PbSO 4 reaction and the kinetics of hydrogen evolution on pure, smooth lead and lead alloy electrodes is studied via galvanostatic polarization in the linear and Tafel domains with and without antimony (0 to 10 mg 1 -1) addition to the H 2SO 4 (3 to 10 M) electrolyte. Phosphoric acid is found to offset significantly the adverse effect of antimony. H 3PO 4 is also found to increase the hydrogen overpotential without affecting the Pb/PbSO 4 reaction. This implies that the open-circuit corrosion of lead and the consequent hydrogen evolution rate on lead are reduced in the presence of H 3PO 4. The beneficial effects of H 3PO 4 additive are found to be optimum at around 20 g 1 -1. Suppression of hydrogen evolution on the negative electrode, a crucial criterion for sealed cell operation, can be achieved using a H 3PO 4 additive.

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

    PubMed

    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.

  17. Development of Advanced Kocite Electrocatalysts for Phosphoric Acid Fuel Cells.

    DTIC Science & Technology

    1981-01-01

    Spring Street University of Florida Waltham, MA 02154 Department of Chemical Engineering Dr. Fred Anson (1) ATTN: Professor R.D. Walker Division of...S WELSH. V W LEYERLE, n S SCARLATA DAAK70-79- C -017 3ULASLIFIEDE D L LEVEL,$ (1 ",*t. ;MENT OF ADVANCED r9CITZE LP.C7ROCATALYsTs QR~ PHOSPHORIC A, 1Pr...se;,- st Irton UrP’",4 ted f-rvjare(,4 ., U. S. Am~y Mobil il) Equiprnet Rese,.’rch and Develo-xrcrit C , rnrnanc !crt Belvoir, Virqinia Cortract N

  18. Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

    NASA Astrophysics Data System (ADS)

    Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal, Ogi, Takashi; Okuyama, Kikuo

    2015-04-01

    A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained by varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.

  19. Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

    SciTech Connect

    Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.; Iskandar, Ferry Abdullah, Mikrajuddin; Khairurrijal; Ogi, Takashi; Okuyama, Kikuo

    2015-04-16

    A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained by varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.

  20. Acid resistance of erbium-doped yttrium aluminum garnet laser-treated and phosphoric acid-etched enamels.

    PubMed

    Kim, Jung-Ho; Kwon, Oh-Won; Kim, Hyung-Il; Kwon, Yong Hoon

    2006-11-01

    To compare the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser ablation and of phosphoric acid etching on the in vitro acid resistance of bovine enamel. Teeth were polished to make the surface flat. The polished enamel was either etched with 37% phosphoric acid for 30 seconds or ablated with a single 33 J/cm2 pulse from an Er:YAG laser. The control specimens were free from acid etching and laser ablation. Changes in crystal structure, dissolved mineral (calcium [Ca] and phosphorus [P]) contents, and calcium distribution in the enamel subsurface after a pH-cycling process were evaluated. After laser treatment, poor crystal structures improved without forming any new phases, such as tricalcium phosphates. Among the tested enamels, dissolved mineral contents were significantly different (P < .05). Er:YAG laser-treated enamels had the lowest mineral dissolution (Ca, 13.78 ppm; P, 6.33 ppm), whereas phosphoric acid-etched enamels had the highest (Ca, 15.90 ppm; P, 7.33 ppm). The reduction rate and reduced depth of calcium content along the subsurface were lowest in Er:YAG laser-treated enamels. The Er:YAG laser-treated enamels are more acid resistant to acid attack than phosphoric acid-etched enamels.

  1. Survey on aging on electrodes and electrocatalysts in phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Stonehart, P.; Hochmuth, J.

    1981-01-01

    The processes which contribute to the decay in performance of electrodes used in phosphoric acid fuel cell systems are discussed. Loss of catalytic surface area, corrosion of the carbon support, electrode structure degradation, electrolyte degradation, and impurities in the reactant streams are identified as the major areas for concern.

  2. Phosphoric acid fuel cell power plant system performance model and computer program

    NASA Technical Reports Server (NTRS)

    Alkasab, K. A.; Lu, C. Y.

    1984-01-01

    A FORTRAN computer program was developed for analyzing the performance of phosphoric acid fuel cell power plant systems. Energy mass and electrochemical analysis in the reformer, the shaft converters, the heat exchangers, and the fuel cell stack were combined to develop a mathematical model for the power plant for both atmospheric and pressurized conditions, and for several commercial fuels.

  3. Current legal and institutional issues in the commercialization of phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Nimmons, J. T.; Sheehy, K. D.; Singer, J. R.; Gardner, T. C.

    1982-01-01

    Legal and institutional factors affecting the development and commercial diffusion of phosphoric acid fuel cells are assessed. Issues for future research and action are suggested. Perceived barriers and potential opportunities for fuel cells in central and dispersed utility operations and on-site applications are reviewed, as well as the general concept of commercialization as applied to emerging energy technologies.

  4. Tuning transport selectivity of ionic species by phosphoric acid gradient in positively charged nanochannel membranes.

    PubMed

    Yang, Meng; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Fan, Xin; Liu, Wei; Liu, Xizhen; Liu, Jianbo; Huang, Jin

    2015-02-03

    The transport of ionic species through a nanochannel plays important roles in fundamental research and practical applications of the nanofluidic device. Here, we demonstrated that ionic transport selectivity of a positively charged nanochannel membrane can be tuned under a phosphoric acid gradient. When phosphoric acid solution and analyte solution were connected by the positively charged nanochannel membrane, the faster-moving analyte through the positively charged nanochannel membrane was the positively charged dye (methylviologen, MV(2+)) instead of the negatively charged dye (1,5-naphthalene disulfonate, NDS(2-)). In other words, a reversed ion selectivity of the nanochannel membranes can be found. It can be explained as a result of the combination of diffusion, induced electroosmosis, and induced electrophoresis. In addition, the influencing factors of transport selectivity, including concentration of phosphoric acid, penetration time, and volume of feed solution, were also investigated. The results showed that the transport selectivity can further be tuned by adjusting these factors. As a method of tuning ionic transport selectivity by establishing phosphoric acid gradient, it will be conducive to improving the separation of ionic species.

  5. Manual of phosphoric acid fuel cell power plant cost model and computer program

    NASA Technical Reports Server (NTRS)

    Lu, C. Y.; Alkasab, K. A.

    1984-01-01

    Cost analysis of phosphoric acid fuel cell power plant includes two parts: a method for estimation of system capital costs, and an economic analysis which determines the levelized annual cost of operating the system used in the capital cost estimation. A FORTRAN computer has been developed for this cost analysis.

  6. Chiral phosphoric acid-catalyzed asymmetric transfer hydrogenation of 3-trifluoromethylthioquinolines.

    PubMed

    Zhou, Ji; Zhang, Qian-Fan; Zhao, Wei-Hao; Jiang, Guo-Fang

    2016-08-07

    A chiral phosphoric acid-catalyzed asymmetric transfer hydrogenation of 3-trifluoromethylthioquinolines has been successfully developed, providing direct and facile access to chiral 2,3-disubstituted 1,2,3,4-tetrahydroquinoline derivatives containing a stereogenic trifluoromethylthio group with up to 99% enantioselectivity.

  7. 40 CFR 180.1210 - Phosphorous acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... requirement of a tolerance. 180.1210 Section 180.1210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1210 Phosphorous acid; exemption from the requirement of a tolerance....

  8. 40 CFR 180.1210 - Phosphorous acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... requirement of a tolerance. 180.1210 Section 180.1210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1210 Phosphorous acid; exemption from the requirement of a tolerance....

  9. 40 CFR 180.1210 - Phosphorous acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... requirement of a tolerance. 180.1210 Section 180.1210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1210 Phosphorous acid; exemption from the requirement of a tolerance....

  10. 40 CFR 180.1210 - Phosphorous acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... requirement of a tolerance. 180.1210 Section 180.1210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1210 Phosphorous acid; exemption from the requirement of a tolerance....

  11. 40 CFR 180.1210 - Phosphorous acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... requirement of a tolerance. 180.1210 Section 180.1210 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1210 Phosphorous acid; exemption from the requirement of a tolerance....

  12. Atomic force microscopy observation of the enamel roughness and depth profile after phosphoric acid etching.

    PubMed

    Loyola-Rodriguez, Juan Pablo; Zavala-Alonso, Veronica; Reyes-Vela, Enrique; Patiño-Marin, Nuria; Ruiz, Facundo; Anusavice, Kenneth J

    2010-01-01

    The aim was to compare the enamel surface roughness (ESR) and absolute depth profile (ADP) (mean peak-to-valley height) by atomic force microscopy (AFM) before and after using four different phosphoric acids. A total of 160 enamel samples from 40 upper premolars were prepared. The inclusion criterion was that the teeth have healthy enamel. Exclusion criteria included any of the following conditions: facial restorations, caries lesions, enamel hypoplasia and dental fluorosis. Evaluations of the ESR and ADP were carried out by AFM. The Mann-Whitney U-test was used to compare continuous variables and the Wilcoxon test was used to analyze the differences between before and after etching. There were statistically significant differences (P phosphoric acids in healthy enamel; Etch-37 and Scotchbond Etching Gel showed higher profiles after etching (P phosphoric acids in healthy enamel. However, consistently Etch-37 and Scotchbond Etching Gel showed the highest increase regarding the ESR and ADP after etching healthy enamel. AFM was a useful tool to study site-specific structural topography changes in enamel after phosphoric acid etching.

  13. Impact of rolling and phosphorous acid on root rot of dry peas in the Pacific Northwest

    USDA-ARS?s Scientific Manuscript database

    Rolling soil after planting is standard in dry pea production areas in the Pacific Northwest but can increase compaction resulting in increase of root rot by oomycetes and other pathogens. Phosphorous acid has been used to manage oomycete pathogens, therefore, the impact of not rolling soil after s...

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

    PubMed

    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.

  15. Cooperative catalysis by palladium and a chiral phosphoric acid: enantioselective amination of racemic allylic alcohols.

    PubMed

    Banerjee, Debasis; Junge, Kathrin; Beller, Matthias

    2014-11-24

    Cooperative catalysis by [Pd(dba)2] and the chiral phosphoric acid BA1 in combination with the phosphoramidite ligand L8 enabled the efficient enantioselective amination of racemic allylic alcohols with a variety of functionalized amines. This catalytic protocol is highly regio- and stereoselective (up to e.r. 96:4) and furnishes valuable chiral amines in almost quantitative yield.

  16. Modification of vital wheat gluten with phosphoric acid to produce high free-solution capacity

    USDA-ARS?s Scientific Manuscript database

    Wheat gluten reacts with phosphoric acid to produce natural superabsorbent gels. The gel properties are defined by Fourier Transform Infra-red (FTIR) spectroscopy, 2-dimensional gel electrophoresis (2DE), and uptake of water, salt solutions, and aqueous ethanol. Temperatures above 120'C and dry cond...

  17. Modification of vital wheat gluten with phosphoric acid to produce high free solution capacity

    USDA-ARS?s Scientific Manuscript database

    Wheat gluten reacts with phosphoric acid in the presence of urea to produce natural superabsorbent gels. Fourier Transform Infra-red (FT-IR) spectroscopy and two-dimensional gel electrophoresis (2DE) reveal chemical changes from the reaction. Temperatures above 120°C and dry conditions create the op...

  18. Conversion of waste cellulose to ethanol. Phase 2: Reaction kinetics with phosphoric acid

    NASA Astrophysics Data System (ADS)

    Moeller, M. B.; Isbell, R. E.

    1982-05-01

    Waste cellulosic material can be hydrolyzed in dilute acid solution to produce fermentable sugars which can then be converted into ethanol. A laboratory investigation was made of the feasibility of using phosphoric acid as the hydrolysis catalyst. The hydrolysis reaction with phosphoric acid solutions was compared with the reaction employing the more conventional dilute sulfuric acid catalyst. The purpose of this research was to examine the hydrolysis step in a proposed process for the conversion of cellulose (from wood, newspapers, municipal solid waste, or other sources) into ethanol - by which a potentially valuable co-product, DICAL (dicalcium phosphate), might be made and sold with or without the lignin content as a fertilizer. The pertinent reaction kinetics for the acid catalyzed production of glucose from cellulose consists of consecutive, pseudo-first order reactions.

  19. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6120 Phosphoric acid, 1,2-eth-a-ne... subject to reporting. (1) The chemical substance identified as phosphoric acid, 1,2-ethanediyl tetrakis(2...

  20. 40 CFR 721.10505 - Phosphoric acid, mixed mono- and diesters with 2-ethyl-1-hexanol and polyethylene glycol mono-C12...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, mixed mono- and... Phosphoric acid, mixed mono- and diesters with 2-ethyl-1-hexanol and polyethylene glycol mono-C12-16-alkyl... identified as phosphoric acid, mixed mono- and diesters with 2-ethyl-1-hexanol and polyethylene glycol mono...

  1. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6120 Phosphoric acid, 1,2-eth-a-ne... subject to reporting. (1) The chemical substance identified as phosphoric acid, 1,2-ethanediyl tetrakis(2...

  2. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6120 Phosphoric acid, 1,2-eth-a-ne... subject to reporting. (1) The chemical substance identified as phosphoric acid, 1,2-ethanediyl tetrakis(2...

  3. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6120 Phosphoric acid, 1,2-eth-a-ne... subject to reporting. (1) The chemical substance identified as phosphoric acid, 1,2-ethanediyl tetrakis(2...

  4. 40 CFR 721.10505 - Phosphoric acid, mixed mono- and diesters with 2-ethyl-1-hexanol and polyethylene glycol mono-C12...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid, mixed mono- and... Phosphoric acid, mixed mono- and diesters with 2-ethyl-1-hexanol and polyethylene glycol mono-C12-16-alkyl... identified as phosphoric acid, mixed mono- and diesters with 2-ethyl-1-hexanol and polyethylene glycol mono...

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

    PubMed

    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.

  6. [Development of dental quick casting with zircon-phosphoric acid investments].

    PubMed

    Fukumoto, R

    1990-03-01

    The application of zircon (ZrSiO4) that has high refractoriness, high thermal conductivity and a low coefficient of thermal expansion, to quick casting investment was studied. Various zircon powders and phosphoric acid solutions were tested with respect to the higher thermal shock resistance. The formulation and properties of zircon-phosphoric acid investment materials such as water/powder ratio, fluidity of slurry, setting time, setting expansion, thermal expansion, thermal analysis, green and fired compressive strength were measured. Formulation of zircon slurry for coating was zircon flower #600 30%, zircon flower #350 10%, and zircon sand CP 60%, and that for sanding was zircon flower #200. The mixing liquid was 15% phosphoric acid and liquid/powder ratio was 0.1. The slurry using phosphoric acid had good fluidity and good workability. The 24-hour green strength was 1 MPa, fired strength was 10 MPa, 24-hour setting expansion was -0.04% and the thermal expansion at 1000 degrees C was 0.31%. Immediately after coating with zircon slurry, the coating layer was dried, sintered and dewaxed by thermal shock. The thermal shock consisted of the following four-step manipulations. The first is hot air drying (50 degrees C, 5 minutes), the second is heat shock (900 degrees C, 3 seconds), the third is redrying (220 degrees C, 3 minutes) and the fourth is dewaxing (550 degrees C, 3 minutes). Small casting of pure titanium and K-metal could be done successfully by the quick casting method using the zircon-phosphoric acid investments. It was found that the total expansion of the secondary investments influenced the casting adapatability.

  7. Effects of phosphoric acid concentration on oxygen reduction kinetics at platinum

    SciTech Connect

    Hsueh, K.L.; Chin, D.T.; Gonzalez, E.R.; Srinivasan, S.

    1984-04-01

    The oxygen reduction reaction was investigated at platinum electrodes in phosphoric acid in the concentration range 0.7M(6.6%) to 17.5M(95%) at 25/sup 0/C using the rotating ring-disk electrode technique. As a complement, cyclic voltammograms on platinum and potentials of zero charge of mercury were obtained as a function of phosphoric aci concentration. The mechanism of the oxygen electrode reaction is discussed in terms of the direct four-electron transfer reduction to water and the formation of hydrogen peroxide as an intermediate in a parallel two-electron transfer reaction The rate constants of the intermediate reaction steps were calculated from the ring-disk data for various potentials and electrolyte concentrations. The characteristics of the reaction were found to be markedly dependent on the concentration of phosphoric acid. These results are interpreted in terms of changes in oxygen solubility, proton activity, and double laye characteristics when passing over from a water to a phosphoric acid solvent structure.

  8. Phosphoric acid distribution and its impact on the performance of polybenzimidazole membranes

    NASA Astrophysics Data System (ADS)

    Mack, Florian; Heissler, Stefan; Laukenmann, Ruben; Zeis, Roswitha

    2014-12-01

    Phosphoric acid doped polybenzimidazole (PBI) is the most common membrane material for high-temperature polymer electrolyte membrane fuel cells (HT-PEMFC). The PBI membrane is usually doped by immersion in hot phosphoric acid. Immersion time and acid temperature affect the doping level of the membrane. In this work we studied the influence of doping time and temperature on the ex-situ and in-situ proton conductivities of poly (2, 5-benzimidazole) (AB-PBI) membranes as well as the fuel cell performance. Confocal Raman microscopy was employed to spatially resolve the acid distribution within the AB-PBI membranes. Therefore the interactions between the basic nitrogen-sides of the AB-PBI polymer and the phosphoric acid protons were investigated. We found that membranes with a 6 h doping time had significantly higher proton conductivity than those doped for only 3 h. In terms of absolute acid up-take, however, the difference was rather small. This result shows that the doping level alone does not define the conductivity of the membrane. The conductivity is also influenced by the micro acid distribution within the membrane. Highest membrane conductivity and fuel cell performance with fumapem AM cross-linked membranes were achieved with a doping time of 6 h and a doping temperature of 120 °C.

  9. Exchange of oxygen isotopes in carbon dioxide-phosphoric [correction of phosporic] acid systems.

    PubMed

    Wachter, E A; Hayes, J M

    1985-01-01

    The rate of exchange of isotopes of oxygen between solutions of concentrated phosphoric acid and CO2 was measured as a function of temperature, acid strength (pressure of water in equilibrium with the solution), pressure of CO2, and surface area of the reaction vessel. At 75 degrees C, significant exchange was found to occur even for the "anhydrous" phosphoric acids, those in which the nominal percentage of H3PO4 in solution is equal to or exceeds 100%. Exchange is much slower at 25 degrees C, but isotopic shifts as large as 0.1% can be observed in 95% H3PO4 at equilibration times approaching 1000 hr. Rates of exchange were found to be dependent upon the vapor pressure of water in equilibrium with the acid solutions. Exchange was found to occur primarily on the surface of the reaction vessel above the solution, with no dependence on total CO2 pressure. These observations indicate that phosphoric acids with nominal concentrations of H3PO4 approaching 105% are preferable for the minimization of exchange between CO2 samples and acid solutions during phosphorolyses of carbonate materials. Moreover, with such acids, significant time--temperature trade-offs are possible, allowing rapid preparation of CO2 at elevated temperatures.

  10. Suicide case due to phosphoric acid ingestion: case report and review of literature.

    PubMed

    Aquila, Isabella; Pepe, Francesca; Di Nunzio, Ciro; Ausania, Francesco; Serra, Arianna; Ricci, Pietrantonio

    2014-11-01

    Ingesting caustic substances represents a common event which may result in serious injuries of the gastrointestinal system. Severity of injury depends on the type of ingested substance: Caustic burns are more frequently associated with acid ingestion and their severity depends on type, concentration, time of exposure, and amount of the ingested substance. We report a case of phosphoric acid ingestion leading to death in a patient with depressive disorder. While reports ingestion of other acids and organophosphates can be found in the literature, there are no reports detailing a death due to phosphoric acid ingestion. We hope that presenting the findings in this case can aid death investigators in future cases that may involve ingestion of such a substance. After autopsy pH, phosphate and calcium ions concentration in the blood were analyzed. The cause of death was due to systemic effects: metabolic acidosis, hypophosphatemia, hypocalcemia, and hyperkalemia.

  11. Manufacture of fermentable sugar solutions from sugar cane bagasse hydrolyzed with phosphoric acid at atmospheric pressure.

    PubMed

    Gámez, Sara; Ramírez, José A; Garrote, Gil; Vázquez, Manuel

    2004-06-30

    Sugar cane bagasse, a renewable and cheap bioresource, was hydrolyzed at 100 degrees C using phosphoric acid at different concentrations (2, 4, or 6%) and reaction times (0-300 min) to obtain fermentable sugar solutions, which have a high concentration of sugars (carbon source for microorganism growth) and a low concentration of growth inhibitors (acetic acid and furfural). Xylose, glucose, arabinose, acetic acid, and furfural were determined following the hydrolysis. Kinetic parameters of mathematical models for predicting these compounds in the hydrolysates were obtained. Derived parameters such as efficiency of hydrolysis or purity of hydrolysates were considered to select as optimal conditions 6% phosphoric acid at 100 degrees C for 300 min. Using these conditions, 21.4 g of sugars L(-)(1) and <4 g of inhibitors L(-)(1) were obtained from the hydrolysis with a water/solid ratio of 8 g of water g(-)(1) of sugar cane bagasse on a dry basis.

  12. On the reaction of iron oxides and oxyhydroxides with tannic and phosphoric acid and their mixtures

    NASA Astrophysics Data System (ADS)

    Beltrán, J. J.; Novegil, F. J.; García, K. E.; Barrero, C. A.

    2010-01-01

    The actions of tannic acid, phosphoric acid and their mixture on lepidocrocite, goethite, superparamagnetic goethite, akaganeite, magnetite, hematite and maghemite for 1 day and 1 month were explored. It was found that these acids form iron tannates and phosphates. Lepidocrocite and magnetite were the iron phases more easily transformed with the mixture of the acids after 1 month of reaction, whereas hematite was the most resistant phase. In the case of goethite, our results suggest that in order to understand properly the action of these acids, we have to take into account its stoichiometry, surface area and degree of crystallinity.

  13. Selective removal of mineral and organic components of bovine enamel by phosphoric acid.

    PubMed

    Torres-Rodríguez, Carolina; Navarro, Alejandro B; Sánchez-Sánchez, Purificación; González-López, Santiago

    2012-08-01

    To follow the chemical composition of bovine enamel during phosphoric acid-induced demineralization. Enamel samples were ground into a fine powder, selecting the 150- and 200-µm fractions in order to obtain a more homogeneous study material. They were immersed in diluted phosphoric acid (0.1%) for increasing durations ranging from 1 to 1440 min. The chemical composition of the solution and enamel powder was determined after each sequential treatment by means of atomic absorption (AA) and Fourier transform infrared (FTIR) spectroscopy. AA data revealed that the amount of calcium mobilized to the solution by the acid treatment was higher at shorter exposure times. However, FTIR data showed that the degree of mineralization of the enamel remained constant during the treatment, indicating that the mineral and organic components were lost at the same rate. Interestingly, poorly crystalline phosphate and carbonate-rich mineral components were preferentially removed and were presumably the main source of calcium released by the acid exposure. FTIR results also demonstrated that organic components rich in hydrophobic groups were preferentially removed during acid treatment. Etching with phosphoric acid produces a nonhomogeneous demineralization of bovine enamel, with the selective removal of poorly crystalline mineral and hydrophobic organic components.

  14. The Bragg reflection integral for potassium acid phthalate

    NASA Astrophysics Data System (ADS)

    Lewis, M.; Maksym, P. A.; Evans, K. D.

    1980-07-01

    Potassium acid phthalate (KAP) analyzers are examined with particular reference to the methods for the measurement and calculation of the wavelength efficiency function which is essential for the quantitative calibration of the instruments. The calculations of the first order Bragg response of KAP embrace three limiting cases so that the separate effects due to a perfect crystal lattice, due to anomalous dispersion, due to absorption and to lattice orders can be seen. Measured data presented include results for fresh and nearly perfect samples, used samples, samples recovered from space, and abused samples. These data will help provide the required calibrations for users of NASA's Solar Maximum Mission spacecraft.

  15. Arachidonic Acid and Other Fatty Acids Directly Activate Potassium Channels in Smooth Muscle Cells

    NASA Astrophysics Data System (ADS)

    Ordway, Richard W.; Walsh, John V.; Singer, Joshua J.

    1989-06-01

    Arachidonic acid, as well as fatty acids that are not substrates for cyclooxygenase and lipoxygenase enzymes, activated a specific type of potassium channel in freshly dissociated smooth muscle cells. Activation occurred in excised membrane patches in the absence of calcium and all nucleotides. Therefore signal transduction pathways that require such soluble factors, including the NADPH-dependent cytochrome P450 pathway, do not mediate the response. Thus, fatty acids directly activate potassium channels and so may constitute a class of signal molecules that regulate ion channels.

  16. Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.

    PubMed

    Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

    2012-11-01

    A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ≈ Erie > Huron > Superior ≈ Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid.

  17. Lignin hydrolysis and phosphorylation mechanism during phosphoric acid-acetone pretreatment: a DFT study.

    PubMed

    Qin, Wu; Wu, Lingnan; Zheng, Zongming; Dong, Changqing; Yang, Yongping

    2014-12-18

    The study focused on the structural sensitivity of lignin during the phosphoric acid-acetone pretreatment process and the resulting hydrolysis and phosphorylation reaction mechanisms using density functional theory calculations. The chemical stabilities of the seven most common linkages (β-O-4, β-β, 4-O-5, β-1, 5-5, α-O-4, and β-5) of lignin in H3PO4, CH3COCH3, and H2O solutions were detected, which shows that α-O-4 linkage and β-O-4 linkage tend to break during the phosphoric acid-acetone pretreatment process. Then α-O-4 phosphorylation and β-O-4 phosphorylation follow a two-step reaction mechanism in the acid treatment step, respectively. However, since phosphorylation of α-O-4 is more energetically accessible than phosphorylation of β-O-4 in phosphoric acid, the phosphorylation of α-O-4 could be controllably realized under certain operational conditions, which could tune the electron and hole transfer on the right side of β-O-4 in the H2PO4- functionalized lignin. The results provide a fundamental understanding for process-controlled modification of lignin and the potential novel applications in lignin-based imprinted polymers, sensors, and molecular devices.

  18. Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Stonehart, P.; Baris, J.; Hockmuth, J.; Pagliaro, P.

    1984-06-01

    The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

  19. Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Stonehart, P.; Baris, J.; Hockmuth, J.; Pagliaro, P.

    1984-01-01

    The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

  20. Study of the chemical mechanisms of the reaction of neutralization of calcium hydroxide by phosphoric acid

    NASA Astrophysics Data System (ADS)

    Elgadi, M.; Mejdoubi, E.; Elansari, L. L.; Essaddek, A.; Abouricha, S.; Lamhamdi, A.

    2005-03-01

    Calcium phosphates reported in this study, are prepared following an acido-basic reaction between phosphoric acid and calcium hydroxide. These phosphates are the brushite, tricalcium phosphate, hydroxyapatite and oxygenated apatite. The follow-up of the reaction by infra-red spectroscopy of absorption showed that the alkaline pH of calcium hydroxide solution, favours the formation of carbonated apatite, at the start of the reaction. Following the addition of phosphoric acid, the pH becomes increasingly favourable to the formation of the desired phase. The insertion of molecular oxygen in the apatitic tunnel is carried out by the use of hydrogen peroxide. The molecular oxygen rate in the apatite is then determined by volumetric analysis.

  1. Recovery of Uranium from Wet Phosphoric Acid by Solvent Extraction Processes

    SciTech Connect

    Beltrami, Denis; Cote, Gérard; Mokhtari, Hamid; Courtaud, Bruno; Moyer, Bruce A.; Chagnes, Alexandre

    2014-11-17

    Between 1951 and 1991, we developed about 17 processes to recover uranium from wet phosphoric acid (WPA), but the viability of these processes was subject to the variation of the uranium price market. Nowadays, uranium from WPA appears to be attractive due to the increase of the global uranium demand resulting from the emergence of developing countries. Moreover, the increasing demand provides impetus for a new look at the applicable technology with a view to improvements as well as altogether new approaches. This paper gives an overview on extraction processes developed in the past to recover uranium from wet phosphoric acid (WPA) as well as the physicochemistry involved in these processes. Recent advances concerning the development of new extraction systems are also reported and discussed.

  2. Potential of phosphoric acid-catalyzed pretreatment and subsequent enzymatic hydrolysis for biosugar production from Gracilaria verrucosa.

    PubMed

    Kwon, Oh-Min; Kim, Sung-Koo; Jeong, Gwi-Taek

    2016-07-01

    This study combined phosphoric acid-catalyzed pretreatment and enzymatic hydrolysis to produce biosugars from Gracilaria verrucosa as a potential renewable resource for bioenergy applications. We optimized phosphoric acid-catalyzed pretreatment conditions to 1:10 solid-to-liquid ratio, 1.5 % phosphoric acid, 140 °C, and 60 min reaction time, producing a 32.52 ± 0.06 % total reducing sugar (TRS) yield. By subsequent enzymatic hydrolysis, a 68.61 ± 0.90 % TRS yield was achieved. These results demonstrate the potential of phosphoric acid to produce biosugars for biofuel and biochemical production applications.

  3. Chiral BINOL-derived phosphoric acids: privileged Brønsted acid organocatalysts for C-C bond formation reactions.

    PubMed

    Zamfir, Alexandru; Schenker, Sebastian; Freund, Matthias; Tsogoeva, Svetlana B

    2010-12-07

    BINOL-derived phosphoric acids have emerged during the last five years as powerful chiral Brønsted acid catalysts in many enantioselective processes. The most successful transformations carried out with chiral BINOL phosphates include C-C bond formation reactions. The recent advances have been reviewed in this article with a focus being placed on hydrocyanations, aldol-type, Mannich, Friedel-Crafts, aza-ene-type, Diels-Alder, as well as cascade and multi-component reactions.

  4. Comparison between phosphoric acid and hydrochloric acid in microabrasion technique for the treatment of dental fluorosis.

    PubMed

    Bassir, Mahshid Mohammadi; Bagheri, Golnaz

    2013-01-01

    To compare the effectiveness of phosphoric acid (H(3)PO(4))-pumice compound with conventional hydrochloric acid (HCl)-pumice compound in treating different severities of dental fluorosis with the microabrasion technique. Sixty-seven anterior teeth from seven patients with different severities of dental fluorosis were treated. In each patient, half of the teeth were treated with HCl-pumice compound and the other half with H(3)PO(4)-pumice compound (split-mouth design). Both treatment compounds were applied for 30-second periods and treatment continued up to 10 minutes. Before and after treatment, standardized photographs were taken. The photographs were compared by two experienced observers unaware of the modality of treatment. Two indices of aesthetics, improvement in appearance (IA) and degree of stain removal (DSR), were determined according to a visual analog scale. The inter- and intra-correlation coefficients were made; then, statistical analyses were calculated using Mann-Whitney and t-test. There were no significant differences in interobserver evaluation. Improvements in aesthetic indices were observed in all fluorotic teeth by both compounds; however, the mean treatment time with HCl-pumice was significantly lower than H(3)PO(4)-pumice. The H(3)PO(4)-pumice compound improved aesthetic indices in fluorotic teeth similar to the HCl-pumice compound.

  5. Comparison between phosphoric acid and hydrochloric acid in microabrasion technique for the treatment of dental fluorosis

    PubMed Central

    Bassir, Mahshid Mohammadi; Bagheri, Golnaz

    2013-01-01

    Purpose: To compare the effectiveness of phosphoric acid (H3PO4)-pumice compound with conventional hydrochloric acid (HCl)-pumice compound in treating different severities of dental fluorosis with the microabrasion technique. Materials and Methods: Sixty-seven anterior teeth from seven patients with different severities of dental fluorosis were treated. In each patient, half of the teeth were treated with HCl-pumice compound and the other half with H3PO4-pumice compound (split-mouth design). Both treatment compounds were applied for 30-second periods and treatment continued up to 10 minutes. Before and after treatment, standardized photographs were taken. The photographs were compared by two experienced observers unaware of the modality of treatment. Two indices of aesthetics, improvement in appearance (IA) and degree of stain removal (DSR), were determined according to a visual analog scale. The inter- and intra-correlation coefficients were made; then, statistical analyses were calculated using Mann-Whitney and t-test. Results: There were no significant differences in interobserver evaluation. Improvements in aesthetic indices were observed in all fluorotic teeth by both compounds; however, the mean treatment time with HCl-pumice was significantly lower than H3PO4-pumice. Conclusion: The H3PO4-pumice compound improved aesthetic indices in fluorotic teeth similar to the HCl-pumice compound. PMID:23349575

  6. Manual of phosphoric acid fuel cell stack three-dimensional model and computer program

    NASA Technical Reports Server (NTRS)

    Lu, C. Y.; Alkasab, K. A.

    1984-01-01

    A detailed distributed mathematical model of phosphoric acid fuel cell stack have been developed, with the FORTRAN computer program, for analyzing the temperature distribution in the stack and the associated current density distribution on the cell plates. Energy, mass, and electrochemical analyses in the stack were combined to develop the model. Several reasonable assumptions were made to solve this mathematical model by means of the finite differences numerical method.

  7. Assessment of the environmental aspects of the DOE phosphoric acid fuel cell program

    NASA Technical Reports Server (NTRS)

    Lundblad, H. L.; Cavagrotti, R. R.

    1983-01-01

    The likely facets of a nationwide phosphoric acid fuel cell (PAFC) power plant commercial system are described. The beneficial and adverse environmental impacts produced by the system are assessed. Eleven specific system activities are characterized and evaluated. Also included is a review of fuel cell technology and a description of DOE's National Fuel Cell Program. Based on current and reasonably foreseeable PAFC characteristics, no environmental or energy impact factor was identified that would significantly inhibit the commercialization of PAFC power plant technology.

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

    PubMed

    Sabatini, Camila

    2013-01-01

    To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS) of two self-etch adhesives to enamel and dentin. 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. 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). 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.

  9. Estimates of the occupational exposure to tenorm in the phosphoric acid production plant in Iran.

    PubMed

    Fathabadi, N; Vasheghani Farahani, M; Moradi, M; Hadadi, B

    2012-09-01

    Phosphate rock is used world wide for manufacturing phosphoric acid and several chemical fertilisers. It is known that the phosphate rock contains various concentrations of uranium, thorium, radium and their daughters. The subject of this study is the evaluation of the radiation exposure to workers in the phosphoric acid production plant due to technologically enhanced naturally occurring radioactive materials that can result from the presence of naturally occurring radioactive materials in phosphate ores used in the manufacturing of phosphoric acid. Radiation exposure due to direct gamma radiation, dust inhalation and radon gas has been investigated and external and internal doses of exposed workers have been calculated. Natural radioactivity due to (40)K, (226)Ra and (232)Th have been measured in phosphate rock, phosphogypsum, chemical fertilisers and other samples by gamma spectrometry system with a high-purity germanium. The average concentrations of (226)Ra and (40)K observed in the phosphate rock are 760 and 80 Bq kg(-1), respectively. Annual effective dose from external radiation had a mean value of ∼0.673 mSv y(-1). Dust sampling revealed greatest values in the storage area. The annual average effective dose from inhalation of long-lived airborne was 0.113 mSv y(-1). Radon gas concentrations in the processing plant and storage area were found to be of the same value as the background. In this study the estimated annual effective doses to workers were below 1 mSv y(-1).

  10. Energy dispersive X-Ray fluorescence determination of thorium in phosphoric acid solutions

    NASA Astrophysics Data System (ADS)

    Mirashi, N. N.; Dhara, Sangita; Kumar, S. Sanjay; Chaudhury, Satyajeet; Misra, N. L.; Aggarwal, S. K.

    2010-07-01

    Energy dispersive X-ray fluorescence studies on determination of thorium (in the range of 7 to 137 mg/mL) in phosphoric acid solutions obtained by dissolution of thoria in autoclave were made. Fixed amounts of Y internal standard solutions, after dilution with equal amount of phosphoric acid, were added to the calibration as well as sample solutions. Solution aliquots of approximately 2-5 µL were deposited on thick absorbent sheets to absorb the solutions and the sheets were presented for energy dispersive X-ray fluorescence measurements. A calibration plot was made between intensity ratios (Th Lα/Y Kα) against respective amounts of thorium in the calibration solutions. Thorium amounts in phosphoric acid samples were determined using their energy dispersive X-ray fluorescence spectra and the above calibration plot. The energy dispersive X-ray fluorescence results, thus obtained, were compared with the corresponding gamma ray spectrometry results and were found to be within average deviation of 2.6% from the respective gamma ray spectrometry values. The average precision obtained in energy dispersive X-ray fluorescence determinations was found to be 4% (1 σ). The energy dispersive X-ray fluorescence method has an advantage over gamma ray spectrometry for thorium determination as the amount of sample required and measurement time is far less compared to that required in gamma ray spectrometry.

  11. Effects of phosphoric acid on bovine enamel bleached with carbamide peroxide.

    PubMed

    de Medeiros, Carmen L S G; González-López, Santiago; Bolaños-Carmona, Maria V; Sanchez-Sanchez, Purificación; Bolaños-Carmona, Jorge

    2008-02-01

    The aim of this study was to measure the demineralization capacity of 37% phosphoric acid on bovine enamel at different time-points after bleaching with 30% carbamide peroxide. Five, 4 x 4-mm sections were obtained from the enamel of 10 bovine incisors. After applying 30% carbamide peroxide (Vivastyle) for 90 min, specimens were stored in artificial saliva for 0, 24, 72 h, or 7 d and then immersed in 37% phosphoric solution. At 15, 30, 60, 90, and 120 s, 5-ml aliquots were extracted. A control group of specimens was not bleached. Ca(2+) concentrations were measured by atomic absorption spectrophotometry. A larger amount of Ca(2+) was extracted from enamel by phosphoric acid after the application of 30% carbamide peroxide. Twenty-four hours after bleaching, significantly more Ca(2+) was extracted from bleached than from control specimens at all time-points, and this greater susceptibility to the action of the acid persisted for at least 1 wk after bleaching.

  12. Superlubricity behavior with phosphoric acid-water network induced by rubbing.

    PubMed

    Li, Jinjin; Zhang, Chenhui; Luo, Jianbin

    2011-08-02

    In present work, a superlubricity phenomenon of phosphoric acid (H(3)PO(4)) was found under ambient conditions. An ultralow friction coefficient of about 0.004 between glass/Si(3)N(4) and sapphire/sapphire tribopairs was obtained under the lubrication of a phosphoric acid aqueous solution (pH 1.5) at high contact pressure (the maximum pressure can reach about 1.65 GPa) after a running-in period of about 600 s. The experimental results indicate that the superlow friction state was very stable for more than 3 h. In such a state, solidlike films formed on the two sliding surfaces, which are hydrates of phosphoric acid with a hydrogen-bonded network according to the Raman spectrum. The superlubricity mechanism is mainly attributed to the hydrogen bond effect that forms a hydrated water layer with low shearing strength, and the dipole-dipole effects that form an interfacial Coulomb repulsion force also make some contributions to low friction. This work may help us to introduce a new approach to superlubricity and may lead to the wide application of superlubricity in future technological and biomedical areas.

  13. Technology development for phosphoric acid fuel cell powerplant, phase 2

    NASA Technical Reports Server (NTRS)

    Christner, L.

    1979-01-01

    A technique for producing an acid inventory control member by spraying FEP onto a partially screened carbon paper backing is discussed. Theoretical analysis of the acid management indicates that the vapor composition of 103% H3PO4 is approximately 1.0 ppm P4O10. An SEM evaluation of corrosion resistance of phenolic resins and graphite/phenolic resin composites in H3PO4 at 185 C shows specific surface etching. Carbonization of graphite/phenolic bipolar plates is achieved without blistering.

  14. Thermodynamic analysis of processes of ammoniation of phosphoric acids

    SciTech Connect

    Rilo, I.P.

    1980-04-01

    A thermochemical analysis is made of processes of ammoniation of orthophosphoric and polyphosphoric acids and estimations are given for thermodynamic properties of products obtained in ammoniation processes: enthalpies of formation, heat capacities and entropies. Coefficients A, B and C are used as determining parameters for the estimations of the thermodynamic properties. 6 references, 1 figure, 2 tables.

  15. Moving single bubble sonoluminescence in phosphoric acid and sulphuric acid solutions.

    PubMed

    Troia, A; Ripa, D Madonna; Spagnolo, R

    2006-04-01

    The phenomenon of sonoluminescence still presents some unsolved aspects. Recently [Y.T. Didenko, K. Suslick, Molecular Emission during Single Bubble Sonoluminescence, Nature 407 (2000) 877-879.], it was found that a single cavitating air bubble in polar aprotic liquids (including formamide and adiponitrile) can produce very strong sonoluminescence while undergoing macroscopic translation movements in the resonator, a condition known as moving single bubble sonoluminescing (MSBSL). Here we describe some experiments conducted in aqueous solutions of phosphoric and sulphuric acid. In these liquid media, it is possible to reproduce MSBSL and luminescence is emitted even if a trapped bubble is subjected to a strong shape instability, named in the literature "jittering phase". When a moving and luminescing bubble was present and the acoustic pressure gradually increased, we observed the generation of a discrete lattice of trapped bubbles. The bubbles in the lattice emit very intense light flashes and can change their position while maintaining the overall spatial distribution in time. Some preliminary results, obtained from Mie-scattering and measurements of relative light intensity, are reported.

  16. Traveling Wave Ion Mobility Mass Spectrometry and Ab Initio Calculations of Phosphoric Acid Clusters

    NASA Astrophysics Data System (ADS)

    Lavanant, Hélène; Tognetti, Vincent; Afonso, Carlos

    2014-04-01

    Positive and negative ion electrospray mass spectra obtained from 50 mM phosphoric acid solutions presented a large number of phosphoric acid clusters: [(H3PO4)n + zH] z+ or [(H3PO4)n - zH] z- , with n up to 200 and z up to 4 for positively charged clusters, and n up to 270 and z up to 7 for negatively charged cluster ions. Ion mobility experiments allowed very explicit separation of the different charge states. Because of the increased pressures involved in ion mobility experiments, dissociation to smaller clusters was observed both in the trap and transfer areas. Voltages along the ion path could be optimized so as to minimize this effect, which can be directly associated with the cleavage of hydrogen bonds. Having excluded the ion mobility times that resulted from dissociated ions, each cluster ion appeared at a single drift time. These drift times showed a linear progression with the number of phosphoric atoms for cluster ions of the same charge state. Cross section calculations were carried out with MOBCAL on DFT optimized geometries with different hydrogen locations and with three types of atomic charges. DFT geometry optimizations yielded roughly spherical structures. Our results for nitrogen gas interaction cross sections showed that values were dependent on the atomic charges definition used in the MOBCAL calculation. This pinpointed the necessity to define a clear theoretical framework before any comparative interpretations can be attempted with uncharacterized compounds.

  17. Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals

    NASA Astrophysics Data System (ADS)

    Rose, A. S. J. Lucia; Selvarajan, P.; Perumal, S.

    2011-10-01

    Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm × 12 mm × 8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.

  18. Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals.

    PubMed

    Rose, A S J Lucia; Selvarajan, P; Perumal, S

    2011-10-15

    Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.

  19. Removal of heavy metals and lanthanides from industrial phosphoric acid process liquors

    SciTech Connect

    Koopman, C.; Witkamp, G.J.; Van Rosmalen, G.M.

    1999-11-01

    To diminish the discharge of heavy metals and lanthanides by the phosphoric acid industry, these impurities have to be removed from the mother liquor before their incorporation in the gypsum crystals. This can best be achieved by means of solvent extraction or ion exchange during the recrystallization of hemihydrate to dihydrate gypsum. Various commercial carriers and two ion-exchange resins were screened for their efficiency and selectivity. Light and heavy lanthanide ions are extracted from the recrystallization acid by didodecylnaphthalenesulfonic acid (Nacure 1052) and di(2-ethylhexyl)phosphoric acid (D2EHPA), and the heavy-metal ions by bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301) and by bis(2,4,4-trimethylpentyl)monothiophosphinic acid (Cyanex 302). Mercury is also extracted by the anion carriers tri(C{sub 8}-C{sub 10})amine (Alamine 336) and tri(C{sub 8}-C{sub 10}) monomethyl ammonium chloride (Aliquat 336). Both Dowex C-500 and Amberlite IR-120 extract lanthanide and heavy-metal ions. Unfortunately, D2EHPA, Nacure 1052, and the two ion-exchange resins also show affinity for ions present in much higher concentrations, like calcium or iron ions.

  20. Bone reactions to oxidized titanium implants with electrochemical anion sulphuric acid and phosphoric acid incorporation.

    PubMed

    Sul, Young-Taeg; Johansson, Carina B; Kang, Yunmo; Jeon, Dong-Gyun; Albrektsson, Tomas

    2002-01-01

    The importance of the surface properties of implants for a successful osseointegration has been emphasized. It is generally known that bone response to implant surfaces is considerably related to the various surface properties. The purpose of this study was to investigate bone tissue reactions to multifactorial biocompatibility of the surface oxide of electrochemically oxidized titanium implants. The ultimate objective was to improve surface quality, resulting in enhancement of clinical outcomes of osseointegrated implants. Three different surface types of commercially pure titanium (c.p. Ti) implants were prepared. Turned implants were used for controls and test implants were prepared by the micro arc oxidation (MAO) method, either in sulphuric acid (S implants) or in phosphoric acid (P implants). Implants were inserted in the femur and tibia of 10 mature New Zealand White rabbits. The bone response was evaluated by biomechanical tests, histology, and histomorphometry. The follow-up time was 6 weeks. The mean peak values of the removal torque showed significant differences between control and test S implants (p =.022) but showed no significant differences between control and test P implants (p =.195) or between test S and test P implants (p =.457). In addition, the histomorphometric comparisons of the bone-to-metal contact around entire implants demonstrated 186% increase in S implants (p =.028) and 232% increase in P implants (p =.028) compared with the paired control groups. Quantification of the bone area in the threads did not show any significant differences. The present results suggest that the primary mode of action in strong bone response to S implants is mechanical interlocking, and to P implants, it is biochemical interaction. It is possible that the phosphate groups in the titanium oxide of P implants provide potential chemical bonding sites for calcium ions and hydroxyapatite of the bone matrix during biologic mineralization. key words: bone responses

  1. Shear bond strength of a resin composite to enamel etched with maleic or phosphoric acid.

    PubMed

    Hallett, K B; Garcia-Godoy, F; Trotter, A R

    1994-10-01

    The purpose of this study was to evaluate the effect of 10 per cent maleic and 37 per cent phosphoric acid on the shear bond strength of Z100 composite resin with Scotchbond Multi-Purpose adhesive to primary and permanent tooth enamel. Four groups of 20 teeth each were established: 1, permanent teeth, 10 per cent maleic acid etched for 15 seconds; 2, permanent teeth, 10 per cent maleic acid etched for 30 seconds; 3, permanent teeth, 37 per cent phosphoric acid etched for 15 seconds; 4, primary teeth, 10 per cent maleic acid etched for 15 seconds. Five teeth from each group were randomly assigned for SEM examination of the etched enamel surface. Scotchbond Multi-Purpose primer and adhesive were applied to the etched enamel surface of the remaining 15 teeth and cured following the manufacturer's instructions. Z100 composite resin was placed in a nylon cylinder and cured for two 40 second intervals. Following thermocycling, the specimens were sheared on an universal testing machine and debonded areas were examined visually with a stereo microscope and with SEM. The mean shear bond strengths in MPa were: 1, 17.00; 2, 14.58; 3, 14.66; 4, 11.18. ANOVA and Student-Newman-Keuls analyses revealed no statistically significant difference among the groups. SEM examination showed the majority of specimens fractured at the adhesive-resin interface.

  2. Hydrolysis of sorghum straw using phosphoric acid: evaluation of furfural production.

    PubMed

    Vázquez, Manuel; Oliva, Martha; Téllez-Luis, Simón J; Ramírez, José A

    2007-11-01

    Sorghum straw is a waste that has been studied scarcely. The main application is its use as raw material for xylose production. Xylose is a hemicellulosic sugar mainly used for its bioconversion toward xylitol. An alternative use could be its conversion toward furfural. The objective of this work was to study the furfural production by hydrolysis of sorghum straw with phosphoric acid at 134 degrees C. Several concentrations of H(3)PO(4) in the range 2-6% and reaction time (range 0-300 min) were evaluated. Kinetic parameters of mathematical models for predicting the concentration of xylose, glucose, arabinose, acetic acid and furfural in the hydrolysates were found. Optimal conditions for furfural production by acid hydrolysis were 6% H(3)PO(4) at 134 degrees C for 300 min, which yielded a solution with 13.7 g furfural/L, 4.0 g xylose/L, 2.9 g glucose/L, 1.1g arabinose/L and 1.2g acetic acid/L. The furfural yield of the process was 0.1336 g furfural/g initial dry matter was obtained. The results confirmed that sorghum straw can be used for furfural production when it is hydrolyzed using phosphoric acid.

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    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.

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

    PubMed

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

    2017-02-16

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Association of low potassium diet and folic acid deficiency in patients with CKD

    PubMed Central

    Hassan, Kamal

    2015-01-01

    Background Most of the folic acid sources are rich also in potassium. Patients with chronic kidney disease (CKD) usually receive a low potassium diet. We investigated the possibility of an association between low potassium diet and folic acid deficiency. Methods In total, 128 CKD patients participated in this cross-sectional study. Sixty-four patients with CKD grades 1 and 2 were on an unrestricted potassium diet when enrolled in the study, and 64 patients with CKD grades 3 and 4 had received instructions to restrict their intake of potassium at least 6 months before enrollment in the study. Subjects were evaluated for daily intake of folic acid (DIFA), daily intake of potassium (DIK), and serum folic acid levels (SFA). Results DIFA correlated with the estimated glomerular filtration rate, the DIK, and the SFA (P<0.001). SFA correlated with the estimated glomerular filtration rate (P<0.001). Mean DIFA and mean SFA were lower among patients with CKD grades 3 and 4 than among those with CKD grades 1 and 2 (P<0.001). The mean DIFA in patients with folic acid deficiency was lower than that in those with SFA ≥7.1 nmol/L (P<0.001). There was lower SFA and threefold greater frequency of folic acid deficiency among patients with CKD grades 3 and 4 who had received instructions to restrict their intake of potassium than among patients with CKD grades 1 and 2 who were on an unrestricted potassium diet. Conclusion A potassium-restricted diet offered to patients with CKD grades 3 and 4 may be associated with folic acid deficiency. Serum levels of folic acid should be investigated before starting potassium restriction in patients with CKD grades 3 and 4, in order to identify individuals with folic acid deficiency or with marginal serum levels who should receive folic acid replacement therapy. PMID:26056461

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

    PubMed

    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 < 0.001) and air abrasion (p < 0.001), with heterogeinity of I(2) = 0% and I(2) = 71%, respectively. It was not found statistical difference when compared phosphoric acid and phosphoric acid combined with Er:YAG 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.

  8. Wet Chemical Oxidation of Organic Waste Using Nitric-Phosphoric Acid Technology

    SciTech Connect

    Pierce, R.A.

    1998-10-06

    Experimental progress has been made in a wide range of areas which support the continued development of the nitric-phosphoric acid oxidation process for combustible, solid organic wastes. An improved understanding of the overall process operation has been obtained, acid recovery and recycle systems have been studied, safety issues have been addressed, two potential final waste forms have been tested, preliminary mass flow diagrams have been prepared, and process flowsheets have been developed. The flowsheet developed is essentially a closed-loop system which addresses all of the internally generated waste streams. The combined activities aim to provide the basis for building and testing a 250-400 liter pilot-scale unit. Variations of the process now must be evaluated in order to address the needs of the primary customer, SRS Solid Waste Management. The customer is interested in treating job control waste contaminated with Pu-238 for shipment to WIPP. As a result, variations for feed preparation, acid recycle, and final form manufacturing must be considered to provide for simpler processing to accommodate operations in high radiation and contamination environments. The purpose of this program is to demonstrate a nitric-phosphoric acid destruction technology which can treat a heterogeneous waste by oxidizing the solid and liquid organic compounds while decontaminating noncombustible items.

  9. Production of technical grade phosphoric acid from incinerator sewage sludge ash (ISSA).

    PubMed

    Donatello, S; Tong, D; Cheeseman, C R

    2010-01-01

    The recovery of phosphorus from sewage sludge ash samples obtained from 7 operating sludge incinerators in the UK using a sulfuric acid washing procedure to produce a technical grade phosphoric acid product has been investigated. The influences of reaction time, sulfuric acid concentration, liquid to solid ratio and source of ISSA on P recovery have been examined. The optimised conditions were the minimum stoichiometric acid requirement, a reaction time of 120 min and a liquid to solid ratio of 20. Under these conditions, average recoveries of between 72% and 91% of total phosphorus were obtained. Product filtrate was purified by passing through a cation exchange column, concentrated to 80% H(3)PO(4) and compared with technical grade H(3)PO(4) specifications. The economics of phosphate recovery by this method are briefly discussed.

  10. Improving phosphorus uptake and wheat productivity by phosphoric acid application in alkaline calcareous soils.

    PubMed

    Akhtar, Muhammad; Yaqub, Muhammad; Naeem, Asif; Ashraf, Muhammad; Hernandez, Vicente Espinosa

    2016-08-01

    Low phosphorus (P) efficiency from existing granular fertilisers necessitates searching for efficient alternatives to improve wheat productivity in calcareous soil. Multi-location trials have shown that phosphoric acid (PA) produced 16% higher wheat grain over commercial P fertilisers, i.e. diammonium phosphate (DAP) and triple superphosphate (TSP). Methods of P application significantly influenced grain yield and the efficiency of methods was observed in the order: PA placement below seed > PA, DAP or TSP fertigation > DAP or TSP broadcast. The sub-surface application of PA produced highest grain yields (mean of all rates), i.e. 4669, 4158 and 3910 kg ha(-1) in Bagh, Bhalwal and Shahpur soil series, respectively. Phosphoric acid at 66 kg P2 O5 ha(-1) was found more effective in increasing gain yield over that of control. Trend in grain P uptake was found similar to that observed for grain yield. Maximum P uptake by grain was recorded at the highest P rate and the lowest at zero P. The significant increase in P uptake with P rates was generally related to the increase in yield rather than its concentration in grain. Phosphorus agronomic efficiency (PAE) and phosphorus recovery efficiency (PRE) were found higher at lower P rate (44 kg P2 O5 ha(-1) ) and decreased with P application. However, PA applied by the either method resulted in higher PAE and PRE compared to DAP and TSP. Phosphoric acid is suggested as an efficient alternative to commercial granular P fertilisers for wheat production in alkaline calcareous soils. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  11. Effects of fluoride treatment on phosphoric acid-etching in primary teeth: an AFM observation.

    PubMed

    Choi, Samjin; Rhee, Yeri; Park, Jeong-Hoon; Lee, Gi-Ja; Kim, Kyung-Sook; Park, Jae-Hong; Park, Young-Guk; Park, Hun-Kuk

    2010-07-01

    The aim of this study was to examine the effect of fluoride application on 37% phosphoric acid-etching by atomic force microscopy (AFM) in primary tooth samples based on a clinical protocol used in a pediatric dental hospital. Enamel samples were prepared from 36 exfoliated and non-carious primary teeth. Primary tooth samples were randomly assigned to one of the four groups based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) pre-treatment. Group 1 received no fluoride application, Group 2 was pre-treated with fluoride and then received acid-etching 2 weeks later. One week separated the fluoride treatment and the acid-etching in Group 3, while Group 4 received acid-etching immediately after the fluoride treatment. The vestibular enamel surfaces of each primary tooth sample were scanned in air at a resolution of 512 x 512 pixels and a scan speed of 0.8 line/s. On the enamel surfaces of the primary teeth after APF pre-treatment, debris were observed although the teeth were smoother than they were prior to APF. As a result, it was concluded that APF treatment is responsible for decreased primary tooth surface roughness. The enamel surfaces etched for 20s showed that acid-etching was effective not only in removing scratches and debris, but also for evaluating enamel rod characteristics. Primary tooth enamel surfaces after etching showed minute structures caused by the decreased hydroxyapatite nanoparticle space, compared to those before etching. Also, acid-etching showed significantly increased roughness effects (p<0.0001, n=9). Finally, as more time elapsed after APF pre-treatment, the roughness was decreased to a lesser degree (p=0.005, n=9). We suggest that primary teeth etching 2 weeks after APF pre-treatment used clinically in pediatric hospitals may be effective to obtain properly etched enamel surfaces.

  12. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  13. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  14. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  15. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  16. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  17. Effect of fungal and phosphoric acid pretreatment on ethanol production from oil palm empty fruit bunches (OPEFB).

    PubMed

    Ishola, Mofoluwake M; Isroi; Taherzadeh, Mohammad J

    2014-08-01

    Oil palm empty fruit bunches (OPEFB), a lignocellulosic residue of palm oil industries was examined for ethanol production. Milled OPEFB exposed to simultaneous saccharification and fermentation (SSF) with enzymes and Saccharomyces cerevisiae resulted just in 14.5% ethanol yield compared to the theoretical yield. Therefore, chemical pretreatment with phosphoric acid, a biological pretreatment with white-rot fungus Pleurotus floridanus, and their combination were carried out on OPEFB prior to the SSF. Pretreatment with phosphoric acid, combination of both methods and just fungal pretreatment improved the digestibility of OPEFB by 24.0, 16.5 and 4.5 times, respectively. During the SSF, phosphoric acid pretreatment, combination of fungal and phosphoric acid pretreatment and just fungal pretreatment resulted in the highest 89.4%, 62.8% and 27.9% of the theoretical ethanol yield, respectively. However, the recovery of the OPEFB after the fungal pretreatment was 98.7%, which was higher than after phosphoric acid pretreatment (36.5%) and combined pretreatment (45.2%). Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    SciTech Connect

    Onoda, Hiroaki 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.

  19. Computer-based phosphoric acid fuel cell analytical tools Descriptions and usages

    NASA Technical Reports Server (NTRS)

    Lu, C.; Presler, A. F.

    1987-01-01

    Simulation models have been developed for the prediction of phosphoric acid fuel cell (PAFC) powerplant system performance under both transient and steady operation conditions, as well as for the design of component configurations and for optimal systems synthesis. These models, which are presently computer-implemented, are an engineering and a system model; the former being solved by the finite difference method to determine the balances and properties of different sections, and the latter using thermodynamic balances to set up algebraic equations that yield physical and chemical properties of the stream for one operating condition.

  20. Non-noble catalysts and catalyst supports for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Mcalister, A. J.

    1981-01-01

    Four different samples of the cubic alloys W sub x-1 Ti sub x C sub 1-y were prepared and found to be active and CO tolerant. When the activities of these cubic alloys were weighted by the reciprocal of the square of the W exchange, they displayed magnitudes and dependence on bulk C deficiency comparable to those of highly active forms of WC. It is concluded that they may offer important insight into the nature of the active sites on, and means for improving the performance of, W-C anode catalysts for use in phosphoric acid fuel cells.

  1. Non-noble catalysts and catalyst supports for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Mcalister, A. J.

    1980-01-01

    Tungsten carbide, which is known to be active for hydrogen oxidation and CO tolerant has a hexagonal structure. Titanium carbide is inactive and has a cubic structure. Four different samples of the cubic alloys Wx-1TixC were prepared and found to be active and CO tolerant. These alloys are of interest as possible phosphoric acid fuel cell catalysts. They also are of interest as opportunities to study the activity of W in a different crystalline environment and to correlate the activities of the surface sites with surface composition.

  2. Non-noble catalysts and catalyst supports for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Mcalister, A. J.

    1981-01-01

    Tungsten carbide, which is active for hydrogen oxidation, is CO tolerant and has a hexagonal structure is discussed. Titanium carbide is inactive and has a cubic structure. Four different samples of the cubic alloys W sub x-1Ti sub XC sub 1-y were found to be active and CO tolerant. When the activities of these cubic alloys are weighted by the reciprocal of the square to those of highly forms of WC. They offer important insight into the nature of the active sites on W-C anode catalysts for use in phosphoric acid fuel cells.

  3. Manual of phosphoric acid fuel cell power plant optimization model and computer program

    NASA Technical Reports Server (NTRS)

    Lu, C. Y.; Alkasab, K. A.

    1984-01-01

    An optimized cost and performance model for a phosphoric acid fuel cell power plant system was derived and developed into a modular FORTRAN computer code. Cost, energy, mass, and electrochemical analyses were combined to develop a mathematical model for optimizing the steam to methane ratio in the reformer, hydrogen utilization in the PAFC plates per stack. The nonlinear programming code, COMPUTE, was used to solve this model, in which the method of mixed penalty function combined with Hooke and Jeeves pattern search was chosen to evaluate this specific optimization problem.

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

    NASA Technical Reports Server (NTRS)

    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.

  5. Enhanced photocatalytic activity of zeolitic imidazolate framework-8 by modification with phosphor tungstic acid

    NASA Astrophysics Data System (ADS)

    Guo, Jiahui; Yang, Lili; Guo, Ruhuai; Yang, Shuo; Chen, Jianbin

    2017-05-01

    Phosphor tungstic acid (PTA)-modified zeolitic imidazolate framework-8 (ZIF-8) catalysts were synthesized for photocatalytic degradation of methylene blue under UV irradiation. The as-prepared catalysts were characterized by the powder X-ray diffraction, N2 adsorption-desorption, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-vis diffuse reflectance spectroscopy techniques. The optimum reaction conditions for photocatalytic degradation of methylene blue on the obtained materials were investigated. The results show that PTA evidently improved the activity of ZIF-8 catalysts because of its fast reversible multi-electron redox transformations. In addition, the reaction mechanism underlying the process was proposed.

  6. Enantioselective Synthesis of β-Arylamines via Chiral Phosphoric Acid-Catalyzed Asymmetric Reductive Amination.

    PubMed

    Kim, Kyung-Hee; Lee, Chun-Young; Cheon, Cheol-Hong

    2015-06-19

    A new method for the synthesis of chiral β-aryl amines via chiral phosphoric acid-catalyzed enantioselective reductive amination of benzyl methyl ketone derivatives with Hantzsch ester was developed. Various chiral β-aryl amines were obtained in high yields and with good to high enantioselectivities. This transformation is applicable to gram-scale reactions, and the catalyst loading can be reduced to 1 mol % without sacrificing any catalytic efficacy. Furthermore, the resulting β-aryl amine was successfully converted into a tetrahydroisoquinoline compound without any loss of enantioselectivity.

  7. SOLVENT EXTRACTION PROCESS FOR THE RECOVERY OF METALS FROM PHOSPHORIC ACID

    DOEpatents

    Bailes, R.H.; Long, R.S.

    1958-11-01

    > A solvent extraction process is presented for recovering metal values including uranium, thorium, and other lanthanide and actinide elements from crude industrial phosphoric acid solutions. The process conslsts of contacting said solution with an immisclble organic solvent extractant containing a diluent and a material selected from the group consisting of mono and di alkyl phosphates, alkyl phosphonates and alkyl phosphites. The uranlum enters the extractant phase and is subsequently recovered by any of the methods known to the art. Recovery is improved if the phosphate solution is treated with a reducing agent such as iron or aluminum powder prior to the extraction step.

  8. Direct asymmetric amination of α-branched cyclic ketones catalyzed by a chiral phosphoric acid.

    PubMed

    Yang, Xiaoyu; Toste, F Dean

    2015-03-11

    Here we report the direct asymmetric amination of α-substituted cyclic ketones catalyzed by a chiral phosphoric acid, yielding products with a N-containing quaternary stereocenter in high yields and excellent enantioselectivities. Kinetic resolution of the starting ketone was also found to occur on some of the substrates under milder conditions, providing enantioenriched α-branched ketones, another important building block in organic synthesis. The utility of this methodology was demonstrated in the short synthesis of (S)-ketamine, the more active enantiomer of this versatile pharmaceutical.

  9. Direct Asymmetric Amination of α-Branched Cyclic Ketones Catalyzed by a Chiral Phosphoric Acid

    PubMed Central

    Yang, Xiaoyu; Toste, F. Dean

    2015-01-01

    Here we report the direct asymmetric amination of α-substituted cyclic ketones catalyzed by a chiral phosphoric acid, yielding products with a N-containing quaternary stereocenter in high yields and excellent enantioselectivities. Kinetic resolution of the starting ketone was also found to occur on some of the substrates under milder conditions, providing enantio-enriched α-branched ketones, another important building block in organic synthesis. The utility of this methodology was demonstrated in the short synthesis of (S)-ketamine, the more active enantiomer of this versatile pharmaceutical. PMID:25719604

  10. Reductive stripping process for the recovery of uranium from wet-process phosphoric acid

    DOEpatents

    Hurst, Fred J.; Crouse, David J.

    1984-01-01

    A reductive stripping flow sheet for recovery of uranium from wet-process phosphoric acid is described. Uranium is stripped from a uranium-loaded organic phase by a redox reaction converting the uranyl to uranous ion. The uranous ion is reoxidized to the uranyl oxidation state to form an aqueous feed solution highly concentrated in uranium. Processing of this feed through a second solvent extraction cycle requires far less stripping reagent as compared to a flow sheet which does not include the reductive stripping reaction.

  11. Origin of Kinetic Resolution of Hydroxy Esters through Catalytic Enantioselective Lactonization by Chiral Phosphoric Acids.

    PubMed

    Changotra, Avtar; Sunoj, Raghavan B

    2016-08-05

    Kinetic resolution is a widely used strategy for separation and enrichment of enantiomers. Using density functional theory computations, the origin of how a chiral BINOL-phosphoric acid catalyzes the selective lactonization of one of the enantiomers of α-methyl γ-hydroxy ester is identified. In a stepwise mechanism, the stereocontrolling transition state for the addition of the hydroxyl group to the si face of the ester carbonyl in the case of the S isomer exhibits a network of more effective noncovalent interactions between the substrate and the chiral catalyst.

  12. Computer-based phosphoric acid fuel cell analytical tools Descriptions and usages

    NASA Technical Reports Server (NTRS)

    Lu, C.; Presler, A. F.

    1987-01-01

    Simulation models have been developed for the prediction of phosphoric acid fuel cell (PAFC) powerplant system performance under both transient and steady operation conditions, as well as for the design of component configurations and for optimal systems synthesis. These models, which are presently computer-implemented, are an engineering and a system model; the former being solved by the finite difference method to determine the balances and properties of different sections, and the latter using thermodynamic balances to set up algebraic equations that yield physical and chemical properties of the stream for one operating condition.

  13. Cassava starch maltodextrinization/monomerization through thermopressurized aqueous phosphoric acid hydrolysis.

    PubMed

    Fontana, J D; Passos, M; Baron, M; Mendes, S V; Ramos, L P

    2001-01-01

    Kinetic conditions were established for the depolymerization of cassava starch for the production of maltodextrins and glucose syrups. Thin-layer chromatography and high-performance liquid chromatography analyses corroborated that the proper H3PO4 strength and thermopressurization range (e.g., 142-170 degrees C; 2.8-6.8 atm) can be successfully explored for such hydrolytic purposes of native starch granules. Because phosphoric acid can be advantageously maintained in the hydrolysate and generates, after controlled neutralization with ammonia, the strategic nutrient triplet for industrial fermentations (C, P, N), this pretreatment strategy can be easily recognized as a recommended technology for hydrolysis and upgrading of starch and other plant polysaccharides. Compared to the classic catalysts, the mandatory desalting step (chloride removal by expensive anion-exchange resin or sulfate precipitation as the calcium-insoluble salt) can be avoided. Furthermore, properly diluted phosphoric acid is well known as an allowable additive in several popular soft drinks such as colas since its acidic feeling in the mouth is compatible and synergistic with both natural and artificial sweeteners. Glycosyrups from phosphorolyzed cassava starch have also been upgraded to high-value single-cell protein such as the pigmented yeast biomass of Xanthophyllomyces dendrorhous (Phaffia rhodozyma), whose astaxanthin (diketo-dihydroxy-beta-carotene) content may reach 0.5-1.0 mg/g of dry yeast cell. This can be used as an ideal complement for animal feeding as well as a natural staining for both fish farming (meat) and poultry (eggs).

  14. The Partitioning of Acetic, Formic, and Phosphoric Acids Between Liquid Water and Steam

    SciTech Connect

    Gruszkiewicz, M.S.; Marshall, S.L.; Palmer, D.A.; Simonson, J.M.

    1999-06-22

    The chemical carryover of impurities and treatment chemicals from the boiler to the steam phase, and ultimately to the low-pressure turbine and condenser, can be quantified based on laboratory experiments preformed over ranges of temperature, pH, and composition. The two major assumptions are that thermodynamic equilibrium is maintained and no deposition, adsorption or decomposition occurs. The most recent results on acetic, formic and phosphoric acids are presented with consideration of the effects of hydrolysis and dimerization reactions. Complications arising from thermal decomposition of the organic acids are discussed. The partitioning constants for these acids and other solutes measured in this program have been incorporated into a simple thermodynamic computer code that calculates the effect of chemical and mechanical carryover on the composition of the condensate formed to varying extents in the water/steam cycle.

  15. Soybean seed protein, oil, fatty acids, and isoflavones altered by potassium fertilizer rates in the midsouth

    USDA-ARS?s Scientific Manuscript database

    Previous research has shown that the effect of potassium fertilizer on soybean ([Glycine max (L.) Merr.] seed composition (protein, oil, fatty acids, and isoflavones) is still largely unknown. Therefore, the objective of this research was to investigate the effects of potassium application on seed p...

  16. Chemical behavior of indigenous impurities (Al, Fe, Si, Mg, F, K, Na, NH{sub 3}, Ca, and SO{sub 4}) during the production of filter-grade wet-process phosphoric acid

    SciTech Connect

    Sullivan, J.M.; Frazier, A.W.; Griffin, C.L.; Grinstead, J.H. Jr.; Kim, Y.K.; Kohler, J.J.

    1992-12-01

    The conventional (dihydrate process) extraction of phosphate rocks with sulfuric acid and subsequent filtration results in a dilute ``filter-grade`` wet-process phosphoric acid (WPA) containing many cationic and anionic impurities which can cause problems during fertilizer production. Most of these problems result because many of the impurities are present in amounts above saturation. This factorial study was designed to define the nature and amounts of components precipitating from simulated filter-grade (28% P{sub 2}O{sub 5}) phosphoric acid at 85, 68, and 25 C, with 2-day retention times. Results show that the precipitation of the iron ammonium and iron potassium phosphates generally provide the largest source of solids in filter-grade phosphoric acid; Mg and Ca fluoroaluminates and alkali fluorosilicates also provide a significant proportion of solids. The distribution of solids between these 3 groups is governed by the F/Si ratio in the acid. The study also delineates the deleterious effect of ammonia contamination (such as from ammonia leakage to gypsum ponds).

  17. Chemical behavior of indigenous impurities (Al, Fe, Si, Mg, F, K, Na, NH[sub 3], Ca, and SO[sub 4]) during the production of filter-grade wet-process phosphoric acid

    SciTech Connect

    Sullivan, J.M.; Frazier, A.W.; Griffin, C.L.; Grinstead, J.H. Jr.; Kim, Y.K.; Kohler, J.J.

    1992-01-01

    The conventional (dihydrate process) extraction of phosphate rocks with sulfuric acid and subsequent filtration results in a dilute ''filter-grade'' wet-process phosphoric acid (WPA) containing many cationic and anionic impurities which can cause problems during fertilizer production. Most of these problems result because many of the impurities are present in amounts above saturation. This factorial study was designed to define the nature and amounts of components precipitating from simulated filter-grade (28% P[sub 2]O[sub 5]) phosphoric acid at 85, 68, and 25 C, with 2-day retention times. Results show that the precipitation of the iron ammonium and iron potassium phosphates generally provide the largest source of solids in filter-grade phosphoric acid; Mg and Ca fluoroaluminates and alkali fluorosilicates also provide a significant proportion of solids. The distribution of solids between these 3 groups is governed by the F/Si ratio in the acid. The study also delineates the deleterious effect of ammonia contamination (such as from ammonia leakage to gypsum ponds).

  18. Recovery of organic extractant from secondary emulsions formed in the extraction of uranium from wet-process phosphoric acid

    SciTech Connect

    Korchnak, J.D.; Fett, R.H.G.

    1984-01-03

    Uranium in wet-process phosphoric acid is extracted with an organic extractant. The pregnant extractant is then centrifuged to separate contaminants from the extractant. Secondary emulsions obtained by separating the contaminants following centrifugation are mixed with water or an acid leaching solution. After mixing, the mixture is centrifuged to separate and recover extractant which is recycled for stripping.

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

    PubMed

    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.

  20. Phosphoric acid doped polybenzimidazole/imidazolium-modified silsesquioxane hybrid proton conducting membranes for anhydrous proton exchange membrane application

    NASA Astrophysics Data System (ADS)

    Lin, Bencai; Chu, Fuqiang; Yuan, Ningyi; Shang, Hui; Ren, Yurong; Gu, Zongzong; Ding, Jianning; Wei, Yingqiang; Yu, Xiaomin

    2014-04-01

    Phosphoric acid doped polybenzimidazole (PBI)/imidazolium-modified silsesquioxane (Im-SiO3/2) hybrid membranes with high proton conductivity at high temperature under anhydrous conditions are synthesized and characterized. The presence of Im-SiO3/2 is confirmed by FT-IR and energy-dispersive X-ray spectroscopy (EDS) mapping of silicon element. The phosphoric acid uptake and proton conductivity of the hybrid membranes increase with the Im-SiO3/2 content, and the conductivity of PBI/Im-SiO3/2-20 reaching 6.3 × 10-2 S cm-1 at 180 °C. Compared with pure PBI membranes, the introduction of Im-SiO3/2 is effective in preventing the release of the phosphoric acid component from the hybrid membranes. The properties of the prepared hybrid membranes indicate their promising prospects in anhydrous proton exchange membrane applications.

  1. Formation of titanium phosphate composites during phosphoric acid decomposition of natural sphene

    NASA Astrophysics Data System (ADS)

    Maslova, Marina V.; Rusanova, Daniela; Naydenov, Valeri; Antzutkin, Oleg N.; Gerasimova, Lidia G.

    2008-12-01

    Decomposition of mineral sphene, CaTiOSiO 4, by H 3PO 4 is investigated in detail. During the dissolution process, simultaneous calcium leaching and formation of titanium phosphate (TiP) take place. The main product of decomposition is a solid titanium phosphate-silica composite. The XRD, solid-sate NMR, IR, TGA, SEM and BET data were used to identify and characterize the composite as a mixture of crystalline Ti(HPO 4) 2·H 2O and silica. When 80% phosphoric acid is used the decomposition degree is higher than 98% and calcium is completely transferred into the liquid phase. Formation of Ti(HPO 4) 2·H 2O proceeds via formation of meta-stable titanium phosphate phases, Ti(H 2PO 4)(PO 4)·2H 2O and Ti(H 2PO 4)(PO 4). The sorption affinities of TiP composites were examined in relation to caesium and strontium ions. A decrease of H 3PO 4 concentration leads to formation of composites with greater sorption properties. The maximum sorption capacity of TiP is observed when 60% H 3PO 4 is used in sphene decomposition. The work demonstrates a valuable option within the Ti(HPO 4) 2·H 2O-SiO 2 composite synthesis scheme, to use phosphoric acid flows for isolation of CaHPO 4·2H 2O fertilizer.

  2. Effect of etching with cysteamine assisted phosphoric acid on gallium nitride surface oxide formation

    NASA Astrophysics Data System (ADS)

    Wilkins, S. J.; Paskova, T.; Ivanisevic, A.

    2013-08-01

    In-situ functionalization of polar GaN was performed by adding cysteamine to a phosphoric acid etchant in order to study its effect on photoluminescence and oxide formation on the surfaces. The functionalization was characterized by atomic force microscopy, x-ray photoelectron spectroscopy, photoluminescence (PL), and water contact angle measurements. Two sets of polar GaN samples with different dislocation densities were evaluated, thin GaN layers residing on sapphire and thick free-standing GaN separated from sapphire substrate aiming to reveal the effect of material quality on in-situ functionalization. The addition of cysteamine to the phosphoric acid solution was found to result in: (i) decreased surface roughness, (ii) no change to hydrophobicity, (iii) decreased oxygen content especially at high-temperature treatments. The effect of the in-situ functionalization on the PL efficiency was more pronounced in the free-standing sample than in the film residing on the sapphire, which was attributed to a higher crystal quality free from strain.

  3. Simultaneous saccharification and fermentation of lignocellulosic residues pretreated with phosphoric acid-acetone for bioethanol production.

    PubMed

    Li, Hui; Kim, Nag-Jong; Jiang, Min; Kang, Jong Won; Chang, Ho Nam

    2009-07-01

    Bermudagrass, reed and rapeseed were pretreated with phosphoric acid-acetone and used for ethanol production by means of simultaneous saccharification and fermentation (SSF) with a batch and fed-batch mode. When the batch SSF experiments were conducted in a 3% low effective cellulose, about 16 g/L of ethanol were obtained after 96 h of fermentation. When batch SSF experiments were conducted with a higher cellulose content (10% effective cellulose for reed and bermudagrass and 5% for rapeseed), higher ethanol concentrations and yields (of more than 93%) were obtained. The fed-batch SSF strategy was adopted to increase the ethanol concentration further. When a higher water-insoluble solid (up to 36%) was applied, the ethanol concentration reached 56 g/L of an inhibitory concentration of the yeast strain used in this study at 38 degrees C. The results show that the pretreated materials can be used as good feedstocks for bioethanol production, and that the phosphoric acid-acetone pretreatment can effectively yield a higher ethanol concentration.

  4. Treatment of phosphoric acid plant wastewater using Fenton's reagent and coagulants.

    PubMed

    Nawghare, P; Rao, N N; Bejankiwar, R; Szyprkowicz, L; Kaul, S N

    2001-01-01

    The results of treatability studies viz., Fenton reaction and physico-chemical (coagulation) treatment using lime, alum, Fe salts and polyaluminium chloride (PAC) performed on wastewater generated from a unit manufacturing technical grade phosphoric acid are reported. Due to low biochemical oxygen demand (BOD) chemical oxygen demand (COD) ratio and very low pH, this wastewater is not amenable for biological treatment. The treatability studies indicated that it is possible to remove 75-80% COD using Fenton's reagent at optimum doses of 1.0 g/L FeSO4 and 2 ml of 30% H2O2. Simultaneously, significant quantities of suspended solids, phosphate and fluoride are also removed. Polyaluminium chloride is found to be more effective towards suspended solids (SS), COD, phosphate and fluoride removal, when compared to other coagulants used in the present study. Addition of an anionic polyelectrolyte (Magnafloc 156) to PAC improved the performance further. A treatment scheme that consists of neutralization (pH 4) + Fenton's reagent + neutralization (pH 7.5) + PAC/Magnafloc 156 is found to be effective in treating phosphoric acid plant wastewater to meet marine discharge standards.

  5. Crystal structure, vibrational spectra and theoretical studies of L-histidinium dihydrogen phosphate-phosphoric acid

    NASA Astrophysics Data System (ADS)

    Ahmed, A. Ben; Feki, H.; Abid, Y.; Boughzala, H.; Minot, C.; Mlayah, A.

    2009-02-01

    In this work, we report a combined experimental and theoretical study on molecular structure and vibrational spectra of L-histidinium dihydrogen phosphate-phosphoric acid, with particular emphasize on the correlation between the intermolecular hydrogen bonds and the hyperpolarizability. Single crystal of L-histidinium dihydrogen phosphate-phosphoric acid has been subjected to X-ray diffraction and Raman spectroscopy. The title compound crystallises in the non-centrosymmetric space group P2 1. Raman spectra have been recorded in the frequency range [150-3350 cm -1]. To obtain a more reliable assignment of the Raman and IR spectra, we have calculated the geometry and the frequencies using HF and DFT methods. All the experimental vibrational bands have been discussed and assigned to normal mode or to combinations and overtones on the basis of our calculations. The optimized geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP and BLYP) are in well agreement with the experimental data. The results of DFT-B3LYP method have shown better fit to experimental ones than HF in evaluating vibrational frequencies. To investigate microscopic second order non-linear optical behaviour of the examined complex, the electric dipole μ, the polarizability α and the hyperpolarizability β were computed using DFT//B3LYP/6-31 G(d) method. According to our calculation, the title compound exhibits non-zero β value revealing microscopic second order NLO behaviour.

  6. Fourier transform infrared characterization of the acidic phosphoric extractant system containing lanthanide

    NASA Astrophysics Data System (ADS)

    Shen, Y.-H.; Yao, S.-K.; Wang, D.-J.; Zhou, Weijin; Li, Ying Xue; Peng, Q.; Wu, JinGuang; Xu, Guang-Xian

    1994-01-01

    The aggregation states and FTIR spectra of the extractive organic phases of saponified HDEHP [di(2-ethylhexyl) phosphoric acid] (1). DMHPA [di(1-methylheptyl) phosphoric acid] (2) and (HDEHP + DMHPA) (3) containing lanthanides were studied, respectively. Transparent solution formed in system (1) while transparent gel formed in system (2) when the loading of lanthanides was more than 50%. The aggregation state of system (3) depends on the molar ratio of HDEHP:DMHPA and the loading percentage of lanthanide. From their FTIR spectra, it can be seen that the P equals O band of gel split into 1164, 1199, and 1232 cm-1, and the P-O-C band split into 1015, 1076, and 1083 cm-1 as well. The results suggested that the aggregation state of lanthanide complex changes considerably in the three systems, and multiple coordination states of p equals o with lanthanide result in the band split. Multiple interactions between P equals O, P-O-C and lanthanide ions form 3-D network in the gel.

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

    PubMed

    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.

  8. The oxidative dealkylation of insecticidal phosphoric acid triesters by mammalian liver enzymes

    PubMed Central

    Donninger, C.; Hutson, D. H.; Pickering, B. A.

    1972-01-01

    1. The dealkylation of the insecticidal phosphoric acid triester, 2-chloro-1-(2,4-dichlorophenyl)vinyl diethyl phosphate, proceeds in mammalian liver slices via an oxidative mechanism and not by hydrolysis. 2. The enzyme that catalyses the reaction is located in the microsomal fraction of liver homogenate and is dependent for activity on molecular oxygen and NADPH. 3. There are large species differences between rat, mouse, rabbit and dog in the activity of the enzymes, the relative rates of dealkylation being 1, 8, 24 and 88 respectively in liver slices. 4. Dimethyl and di-isopropyl phosphate triesters are also dealkylated by rabbit liver microsomal preparations. 5. The mechanism of dealkylation involves hydroxylation at the α-carbon atom of an alkyl group, which is removed as the corresponding aldehyde, and is thus analogous to that of similar reactions catalysed by the microsomal mixed-function oxidases. 6. The relevance of these findings in the toxicology of phosphoric acid triesters is discussed. PMID:5075276

  9. Determination of bismuth in pharmaceutical products using phosphoric acid as molecular probe by resonance light scattering.

    PubMed

    Yun, Yanru; Cui, Fengling; Geng, Shaoguang; Jin, Jianhua

    2012-01-01

    A novel method for the sensitive determination of bismuth(III) in pharmaceutical products using phosphoric acid as a molecular probe by resonance light scattering (RLS) is discussed. In 0.5 mol/L phosphoric acid (H3 PO4) medium, bismuth(III) reacted with PO4 (3-) to form an ion association compound, which resulted in the significant enhancement of RLS intensity and the appearance of the corresponding RLS spectral characteristics. The maximum scattering peak of the system existed at 364 nm. Under optimal conditions, there was linear relationship between the relative intensity of RLS and concentration of bismuth(III) in the range of 0.06-10.0 µg/mL for the system. A low detection limit for bismuth(III) of 3.22 ng/mL was achieved. The relative standard deviations (RSD) for the determination of 0.40 and 0.80 µg/mL bismuth(III) were 2.1% and 1.1%, respectively, for five determinations. Based on this fact, a simple, rapid, and sensitive method was developed for the determination of bismuth(III) at nanogram level by RLS technique with a common spectrofluorimeter. This analytical system was successfully applied to determine the trace amounts of bismuth(III) in pharmaceutical products, which was in good agreement with the results obtained by atomic absorption spectrometry (AAS).

  10. Arundo donax cane as a precursor for activated carbons preparation by phosphoric acid activation.

    PubMed

    Vernersson, T; Bonelli, P R; Cerrella, E G; Cukierman, A L

    2002-06-01

    Canes from Arundo donax, a herbaceous rapid-growing plant, were used as precursor for activated carbon preparation by phosphoric acid activation under a self-generated atmosphere. The influence of the carbonization temperature in the range 400-550 degrees C and of the weight ratio phosphoric acid to precursor (R = 1.5-2.5) on the developed porous structure of the resulting carbons was studied for 1 h of carbonization time. Surface properties of the activated carbons were dependent on a combined effect of the conditions employed. Carbons developed either with R = 1.5 over the range 400-500 degrees C, or with R = 2 at 500 degrees C exhibited surface areas of around 1100 m2/g, the latter conditions promoting a larger pore volume and enhanced mesoporous character. For both ratios, temperature above 500 degrees C led to reduction in porosity development. A similar effect was found for the highest ratio (R = 2.5) and 500 degrees C. The influence of carrying out the carbonization either for times shorter than 1 h or under flowing N2 was also examined at selected conditions (R = 2, 500 degrees C). Shorter times induced increase in the surface area (approximately 1300 m2/g), yielding carbons with smaller mean pore radius. Activated carbons obtained under flowing N2 possessed predominant microporous structures and larger ash contents than the samples derived in the self-generated atmosphere.

  11. Investigations on the mechanism of superlubricity achieved with phosphoric acid solution by direct observation

    NASA Astrophysics Data System (ADS)

    Li, Jinjin; Ma, Liran; Zhang, Shaohua; Zhang, Chenhui; Liu, Yuhong; Luo, Jianbin

    2013-09-01

    In this work, the contact region between a Si3N4 ball and a SiO2 plate with the lubrication of phosphoric acid solution is observed directly by an optical microscope combined with a Raman microscope to understand the superlubricity mechanism. It is found that the wear on the friction surfaces mainly occurs at the beginning of the test and nearly disappears after the friction coefficient reduces to 0.05. When the superlubricity appears (μ = 0.004), there is only a limited amount of solution available to the contact (forming starvation state), resulting in an "H" distribution surrounding the contact region. Moreover, it is observed that the hydrogen bond effect in the solution is enhanced with time going by, and finally a thin film with hydrogen bond network among H3PO4, H2PO4-, and H2O is formed on the friction surfaces, leading to the superlubricity. By employing this direct observation approach, the structure of the confined solution and the superlubricity mechanism of phosphoric acid solution are finally investigated and discussed.

  12. Potential uranium supply from phosphoric acid: A U.S. analysis comparing solvent extraction and Ion exchange recovery

    DOE PAGES

    Kim, Haeyeon; G. Eggert, Roderick; W. Carlsen, Brett; ...

    2016-06-16

    Phosphate rock contains significant amounts of uranium, although in low concentrations. Recovery of uranium as a by-product from phosphoric acid, an intermediate product produced during the recovery of phosphorus from phosphate rock, is not unprecedented. Phosphoric acid plants ceased to produce uranium as a by-product in the early 1990s with the fall of uranium prices. In the last decade, this topic has regained attention due to higher uranium prices and expected increase in demand for uranium. Our study revisits the topic and estimates how much uranium might be recoverable from current phosphoric acid production in the United States and whatmore » the associated costs might be considering two different recovery processes: solvent extraction and ion exchange. Based on U.S. phosphoric acid production in 2014, 5.5 million pounds of U3O8 could have been recovered, more than domestic U.S. mine production of uranium in the same year. Annualized costs for a hypothetical uranium recovery plant are US$48-66 per pound U3O8 for solvent extraction, the process used historically in the United States to recover uranium from phosphoric acid. For ion exchange, not yet proven at a commercial scale for uranium recovery, the estimated costs are US$33-54 per pound U3O8. Our results suggest that it is technically possible for the United States to recover significant quantities of uranium from current phosphoric acid production. And for this type of uranium production to be economically attractive on a large scale, either recovery costs must fall or uranium prices rise.« less

  13. Potential uranium supply from phosphoric acid: A U.S. analysis comparing solvent extraction and Ion exchange recovery

    SciTech Connect

    Kim, Haeyeon; G. Eggert, Roderick; W. Carlsen, Brett; W. Dixon, Brent

    2016-06-16

    Phosphate rock contains significant amounts of uranium, although in low concentrations. Recovery of uranium as a by-product from phosphoric acid, an intermediate product produced during the recovery of phosphorus from phosphate rock, is not unprecedented. Phosphoric acid plants ceased to produce uranium as a by-product in the early 1990s with the fall of uranium prices. In the last decade, this topic has regained attention due to higher uranium prices and expected increase in demand for uranium. Our study revisits the topic and estimates how much uranium might be recoverable from current phosphoric acid production in the United States and what the associated costs might be considering two different recovery processes: solvent extraction and ion exchange. Based on U.S. phosphoric acid production in 2014, 5.5 million pounds of U3O8 could have been recovered, more than domestic U.S. mine production of uranium in the same year. Annualized costs for a hypothetical uranium recovery plant are US$48-66 per pound U3O8 for solvent extraction, the process used historically in the United States to recover uranium from phosphoric acid. For ion exchange, not yet proven at a commercial scale for uranium recovery, the estimated costs are US$33-54 per pound U3O8. Our results suggest that it is technically possible for the United States to recover significant quantities of uranium from current phosphoric acid production. And for this type of uranium production to be economically attractive on a large scale, either recovery costs must fall or uranium prices rise.

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

    PubMed

    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.

  15. Phosphoric acid esters cannot replace polyvinylphosphonic acid as phosphoprotein analogs in biomimetic remineralization of resin-bonded dentin

    PubMed Central

    Mai, Sui; Kim, Young Kyung; Toledano, Manuel; Breschi, Lorenzo; Ling, Jun Qi; Pashley, David H.; Tay, Franklin R.

    2009-01-01

    Polyvinylphosphonic acid (PVPA), a biomimetic analog of phosphoproteins, is crucial for recruiting polyacrylic acid (PAA)-stabilized amorphous calcium phosphate nanoprecursors during biomimetic remineralization of dentin collagen matrices. This study tested the null hypothesis that phosphoric acid esters of methacrylates in dentin adhesives cannot replace PVPA during bimimetic remineralization of resin-dentin interfaces. Human dentin specimens were bonded with: I) XP Bond, an etch-and-rinse adhesive using moist bonding; II) XP Bond using dry bonding; and III) Adper Prompt L-Pop, a self-etching adhesive. The control medium contained only set Portland cement and a simulated body fluid (SBF) without any biomimetic analog. Two experimental Portland cement/SBF remineralization media were evaluated: the first contained PAA as the sole biomimetic analog, the second contained PAA and PVPA as dual biomimetic analogs. No remineralization of the resin-dentin interfaces could be identified from specimens immersed in the control medium. After 2–4 months in the first experimental medium, specimens exhibited either no remineralization or large crystal formation within hybrid layers. Only specimens immersed in the second remineralization medium produced nanocrystals that accounted for intrafibrillar remineralization within hybrid layers. The null hypothesis could not be rejected; phosphoric acid esters in dentin adhesives cannot replace PVPA during biomimetic remineralization of adhesive-bonded dentin. PMID:19481792

  16. Recovery of Uranium from Wet Phosphoric Acid by Solvent Extraction Processes

    DOE PAGES

    Beltrami, Denis; Cote, Gérard; Mokhtari, Hamid; ...

    2014-11-17

    Between 1951 and 1991, we developed about 17 processes to recover uranium from wet phosphoric acid (WPA), but the viability of these processes was subject to the variation of the uranium price market. Nowadays, uranium from WPA appears to be attractive due to the increase of the global uranium demand resulting from the emergence of developing countries. Moreover, the increasing demand provides impetus for a new look at the applicable technology with a view to improvements as well as altogether new approaches. This paper gives an overview on extraction processes developed in the past to recover uranium from wet phosphoricmore » acid (WPA) as well as the physicochemistry involved in these processes. Recent advances concerning the development of new extraction systems are also reported and discussed.« less

  17. High surface area porous carbons prepared from hydrochars by phosphoric acid activation.

    PubMed

    Wang, Lili; Guo, Yupeng; Zou, Bo; Rong, Chunguang; Ma, Xiaoyu; Qu, Yuning; Li, Ying; Wang, Zichen

    2011-01-01

    In the present work, a new route for preparation of high-performance porous carbons under mild conditions was reported. The high surface area (2700 m2/g) and large pore volume (1.98 cm3/g) porous carbons were prepared from hydrochars by conventional phosphoric acid activation method. The hydrochars described here can be obtained from sulfuric acid hydrolysis of rice husk via dehydration, polymerization and carbonization. A specific capacitance of 130 F g(-1) was achieved by using the porous carbon, indicating that the porous carbon prepared by this route has good electrochemical performance. Furthermore, the localized graphitic nature of the porous carbon was proved by X-ray diffraction pattern.

  18. Recovery of uranium from phosphoric acid medium by polymeric composite beads encapsulating organophosphorus extractants

    SciTech Connect

    Singh, D.K.; Yadav, K.K.; Varshney, L.; Singh, H.

    2013-07-01

    The present study deals with the preparation and evaluation of the poly-ethersulfone (PES) based composite beads encapsulating synergistic mixture of D2EHPA and Cyanex 923 (at 4:1 mole ratio) for the separation of uranium from phosphoric acid medium. SEM was used for the characterization of the composite materials. Addition of 1% PVA (polyvinyl alcohol) improved the internal morphology and porosity of the beads. Additionally, microscopic examination of the composite bead confirmed central coconut type cavity surrounded by porous polymer layer of the beads through which exchange of metal ions take place. Effect of various experimental variables including aqueous acidity, metal ion concentration in aqueous feed, concentration of organic extractant inside the beads, extractant to polymer ratio, liquid to solid (L/S) ratio and temperature on the extraction of uranium was studied. Increase in acidity (1-6 M), L/S ratio (1- 10), metal ion concentration (0.2-3 g/L U{sub 3}O{sub 8}) and polymer to extractant ratio (1:4 -1:10) led to decrease in extraction of uranium. At 5.5 M (comparable to wet process phosphoric acid concentration) the extraction of uranium was about 85% at L/S ratio 5. Increase in extractant concentration inside the bead resulted in enhanced extraction of metal ion. Increase in temperature in the range of 30 to 50 Celsius degrees increased the extraction, whereas further increase to 70 C degrees led to the decrease in extraction of uranium. Amongst various reagents tested, stripping of uranium was quantitative by 12% Na{sub 2}CO{sub 3} solution. Polymeric beads were found to be stable and reusable up-to 10 cycles of extraction/stripping. (authors)

  19. Self-assembled nanostructured cellulose prepared by a dissolution and regeneration process using phosphoric acid as a solvent.

    PubMed

    Hao, Xiaoxia; Shen, Wei; Chen, Zhigang; Zhu, Jiaming; Feng, Li; Wu, Zongwei; Wang, Peng; Zeng, Xiaoxiong; Wu, Tao

    2015-06-05

    This report describes a "green" method for preparing self-assembled nanostructured cellulose through a dissolution and regeneration process. Cold phosphoric acid is used to dissolve cellulose in order to convert crystalline cellulose into its molecular form. Self-assembly of cellulose molecules into nanostructured cellulose is achieved by using water to regenerate cellulose. By controlling the temperature and time of the phosphoric acid treatment between dissolution and regeneration, the degree of polymerization and the degree of substitution of phosphorous for the regenerated celluloses can be tuned. As a result, cellulose nanofibers or nanospheres can be obtained when the treatment temperature is set to 5 or 50°C, respectively. X-ray analysis shows that the cellulose nanofibers are amorphous and that the cellulose nanospheres are structured similarly to cellulose II with crystallinity indexes between 56 and 73%. Our method offers a "green" process for preparing nanostructured celluloses in high yields. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. How do crop plants tolerate acid soils? Mechanisms of aluminum tolerance and phosphorous efficiency.

    PubMed

    Kochian, Leon V; Hoekenga, Owen A; Pineros, Miguel A

    2004-01-01

    Acid soils significantly limit crop production worldwide because approximately 50% of the world's potentially arable soils are acidic. Because acid soils are such an important constraint to agriculture, understanding the mechanisms and genes conferring tolerance to acid soil stress has been a focus of intense research interest over the past decade. The primary limitations on acid soils are toxic levels of aluminum (Al) and manganese (Mn), as well as suboptimal levels of phosphorous (P). This review examines our current understanding of the physiological, genetic, and molecular basis for crop Al tolerance, as well as reviews the emerging area of P efficiency, which involves the genetically based ability of some crop genotypes to tolerate P deficiency stress on acid soils. These are interesting times for this field because researchers are on the verge of identifying some of the genes that confer Al tolerance in crop plants; these discoveries will open up new avenues of molecular/physiological inquiry that should greatly advance our understanding of these tolerance mechanisms. Additionally, these breakthroughs will provide new molecular resources for improving crop Al tolerance via both molecular-assisted breeding and biotechnology.

  1. Formation of titanium phosphate composites during phosphoric acid decomposition of natural sphene

    SciTech Connect

    Maslova, Marina V.; Rusanova, Daniela Naydenov, Valeri; Antzutkin, Oleg N.; Gerasimova, Lidia G.

    2008-12-15

    Decomposition of mineral sphene, CaTiOSiO{sub 4}, by H{sub 3}PO{sub 4} is investigated in detail. During the dissolution process, simultaneous calcium leaching and formation of titanium phosphate (TiP) take place. The main product of decomposition is a solid titanium phosphate-silica composite. The XRD, solid-sate NMR, IR, TGA, SEM and BET data were used to identify and characterize the composite as a mixture of crystalline Ti(HPO{sub 4}){sub 2}.H{sub 2}O and silica. When 80% phosphoric acid is used the decomposition degree is higher than 98% and calcium is completely transferred into the liquid phase. Formation of Ti(HPO{sub 4}){sub 2}.H{sub 2}O proceeds via formation of meta-stable titanium phosphate phases, Ti(H{sub 2}PO{sub 4})(PO{sub 4}).2H{sub 2}O and Ti(H{sub 2}PO{sub 4})(PO{sub 4}). The sorption affinities of TiP composites were examined in relation to caesium and strontium ions. A decrease of H{sub 3}PO{sub 4} concentration leads to formation of composites with greater sorption properties. The maximum sorption capacity of TiP is observed when 60% H{sub 3}PO{sub 4} is used in sphene decomposition. The work demonstrates a valuable option within the Ti(HPO{sub 4}){sub 2}.H{sub 2}O-SiO{sub 2} composite synthesis scheme, to use phosphoric acid flows for isolation of CaHPO{sub 4}.2H{sub 2}O fertilizer. - Graphical abstract: A new synthesis scheme for preparation of composite titanium phosphate (TiP) ion-exchangers upon one-stage decomposition process of natural sphene with phosphoric acid is presented. Syntheses of {alpha}-TiP-silica composites proceed via formation of meta-stable titanium phosphate phases. The concentration of H{sub 3}PO{sub 4} determines the porosity of final products and their sorption affinities.

  2. Modelling malic acid accumulation in fruits: relationships with organic acids, potassium, and temperature.

    PubMed

    Lobit, Philippe; Genard, Michel; Soing, Patrick; Habib, Robert

    2006-01-01

    Malic acid production, degradation, and storage during fruit development have been modelled. The model assumes that malic acid content is determined essentially by the conditions of its storage in the mesocarp cells, and provides a simplified representation of the mechanisms involved in the accumulation of malate in the vacuole and their regulation by thermodynamic constraints. Solving the corresponding system of equations made it possible to predict the malic acid content of the fruit as a function of organic acids, potassium concentration, and temperature. The model was applied to peach fruit, and parameters were estimated from the data of fruit development monitored over 2 years. The predictions were in good agreement with experimental data. Simulations were performed to analyse the behaviour of the model in response to variations in composition and temperature.

  3. Evaluating EDTA as a substitute for phosphoric acid-etching of enamel and dentin.

    PubMed

    Imbery, Terence A; Kennedy, Matthew; Janus, Charles; Moon, Peter C

    2012-01-01

    Matrix metalloproteinases (MMPs) are proteolytic enzymes released when dentin is acid-etched. The enzymes are capable of destroying unprotected collagen fibrils that are not encapsulated by the dentin adhesive. Chlorhexidine applied after etching inhibits the activation of released MMPs, whereas neutral ethylenediamine tetra-acetic acid (EDTA) prevents the release of MMPs. The purpose of this study was to determine if conditioning enamel and dentin with EDTA can be a substitute for treating acid-etching enamel and dentin with chlorhexidine. A column of composite resin was bonded to enamel and dentin after conditioning. Shear bond strengths were evaluated after 48 hours and after accelerated aging for three hours in 12% sodium hypochlorite. Shear bond strengths ranged from 15.6 MP a for accelerated aged EDTA enamel specimens to 26.8 MPa for dentin conditioned with EDTA and tested after 48 hours. A three-way ANOVA and a Tukey HSD test found statistically significant differences among the eight groups and the three independent variables (P < 0.05). EDTA was successfully substituted for phosphoric acid-etched enamel and dentin treated with chlorhexidine. Interactions of conditioning agent and aging were significant for dentin but not for enamel. In an effort to reduce the detrimental effects of MMPs, conditioning enamel and dentin with EDTA is an alternative to treating acid-etched dentin and enamel with chlorhexidine.

  4. IN-VITRO FORMATION OF PYROMORPHITE VIA REACTION OF PB SOURCES WITH SOFT-DRINK PHOSPHORIC ACID

    EPA Science Inventory

    The risk of Pb adsorption into the body may be greatly diminished when accompanied by a phosphate sink. One of the most labile, albeit not healthiest, forms of phosphate consumed in the human diet is derived from cola soft drinks that use phosphoric acid as a preservative and als...

  5. IN-VITRO FORMATION OF PYROMORPHITE VIA REACTION OF PB SOURCES WITH SOFT-DRINK PHOSPHORIC ACID

    EPA Science Inventory

    The risk of Pb adsorption into the body may be greatly diminished when accompanied by a phosphate sink. One of the most labile, albeit not healthiest, forms of phosphate consumed in the human diet is derived from cola soft drinks that use phosphoric acid as a preservative and als...

  6. Efficacy of fungicide combinations, phosphoric acid, and plant extract from stinging nettle on potato late blight management and tuber yield

    USDA-ARS?s Scientific Manuscript database

    Late blight, caused by Phytophthora infestans is a major constraint to potato production. Inadequate management of the disease has often resulted in heavy losses in various production regions. We assessed the efficacy of fungicides, phosphoric acid, and stinging nettle plant extract combinations for...

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

    PubMed

    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.

  8. Studies on the in vitro and in vivo antifungal activity of fosetyl-al and phosphorous acid

    Treesearch

    Mark A. Fenn; M.D. Coffey

    1984-01-01

    In a low-phosphate medium fosetyl-Al showed a much higher activity in vitro against Phytophthora than previously reported in the literature. Both fosetyl-Al, and more particularly phosphorous acid (H3PO3), were highly inhibitory in vitro against several species of Phytophthora....

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

    PubMed

    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.

  10. Deciphering the origin of cooperative catalysis by dirhodium acetate and chiral spiro phosphoric acid in an asymmetric amination reaction.

    PubMed

    Kisan, Hemanta K; Sunoj, Raghavan B

    2014-12-04

    The mechanism of asymmetric amination of diazo-acetate by tert-butyl carbamate catalyzed by dirhodium tetra(trifluoro)acetate and chiral SPINOL-phosphoric acid is examined using DFT (M06 and B3LYP) computations. A cooperative participation of both catalysts is noticed in the stereo-controlling transition state of the reaction.

  11. Highly enantioselective aza-Diels-Alder reaction of 1-azadienes with enecarbamates catalyzed by chiral phosphoric acids.

    PubMed

    He, Long; Laurent, Gregory; Retailleau, Pascal; Folléas, Benoît; Brayer, Jean-Louis; Masson, Géraldine

    2013-10-11

    On demand: A highly enantio- and diastereoselective synthesis of 6-amino- trisubstituted tetrahydropyridine compounds has been developed through the inverse-electron-demand aza-Diels-Alder reaction of N-aryl α,β-unsaturated ketimines with enecarbamates (E)-1. Chiral phosphoric acid catalysts achieve simultaneous activation of both the 1-azadiene and dienophile partners.

  12. Determination of real oxidation potentials of the Bk /SUP IV/ -Bk /SUP III/ pair in phosphoric acid solutions

    SciTech Connect

    Perevalov, S.A.; Kulyako, Y.M.; Lebedev, I.A.; Myasoedov, B.F.

    1986-03-01

    The authors measure the oxidation potential of the Bk(IV)-Bk(III) pair in H3PO4 solutions by a direct spectroelectrchemical method. When the phosphoric acid concentration is increased from 3 to 10 M, its value decreases from 1.123 to 1.065 V (with respect to a normal hydrogen electrode).

  13. Effect of EDTA and Phosphoric Acid Pretreatment on the Bonding Effectiveness of Self-Etch Adhesives to Ground Enamel

    PubMed Central

    Ibrahim, Ihab M.; Elkassas, Dina W.; Yousry, Mai M.

    2010-01-01

    Objectives: This in vitro study determined the effect of enamel pretreatment with phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of strong, intermediary strong, and mild self-etching adhesive systems. Methods: Ninety sound human premolars were used. Resin composite cylinders were bonded to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper Prompt L-Pop (pH=0.9–1.0), intermediary strong AdheSE (pH=1.6–1.7), and mild Frog (pH=2). Adhesive systems were applied either according to manufacturer instructions (control) or after pretreatment with either phosphoric acid or EDTA (n=10). After 24 hours, shear bond strength was tested using a universal testing machine at a cross-head speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography and resin/enamel interfaces as well as representative fractured enamel specimens were examined using scanning electron microscopy (SEM). Results: Neither surface pretreatment statistically increased the mean shear bond strength values of either the strong or the intermediary strong self-etching adhesive systems. However, phosphoric acid pretreatment significantly increased the mean shear bond strength values of the mild self-etching adhesive system. SEM examination of enamel surface topography showed that phosphoric acid pretreatment deepened the same etching pattern of the strong and intermediary strong adhesive systems but converted the irregular etching pattern of the mild self-etching adhesive system to a regular etching pattern. SEM examination of the resin/enamel interface revealed that deepening of the etching pattern was consistent with increase in the length of resin tags. EDTA pretreatment had a negligible effect on ultra-morphological features. Conclusions: Use of phosphoric acid pretreatment can be beneficial with mild self-etching adhesive systems for bonding to enamel. PMID:20922162

  14. Quantifying phosphoric acid in high-temperature polymer electrolyte fuel cell components by X-ray tomographic microscopy.

    PubMed

    Eberhardt, S H; Marone, F; Stampanoni, M; Büchi, F N; Schmidt, T J

    2014-11-01

    Synchrotron-based X-ray tomographic microscopy is investigated for imaging the local distribution and concentration of phosphoric acid in high-temperature polymer electrolyte fuel cells. Phosphoric acid fills the pores of the macro- and microporous fuel cell components. Its concentration in the fuel cell varies over a wide range (40-100 wt% H3PO4). This renders the quantification and concentration determination challenging. The problem is solved by using propagation-based phase contrast imaging and a referencing method. Fuel cell components with known acid concentrations were used to correlate greyscale values and acid concentrations. Thus calibration curves were established for the gas diffusion layer, catalyst layer and membrane in a non-operating fuel cell. The non-destructive imaging methodology was verified by comparing image-based values for acid content and concentration in the gas diffusion layer with those from chemical analysis.

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

    PubMed

    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.

  16. Process for the removal of acid forming gases from exhaust gases and production of phosphoric acid

    DOEpatents

    Chang, Shih-Ger; Liu, David K.

    1992-01-01

    Exhaust gases are treated to remove NO or NO.sub.x and SO.sub.2 by contacting the gases with an aqueous emulsion or suspension of yellow phosphorous preferably in a wet scrubber. The addition of yellow phosphorous in the system induces the production of O.sub.3 which subsequently oxidizes NO to NO.sub.2. The resulting NO.sub.2 dissolves readily and can be reduced to form ammonium ions by dissolved SO.sub.2 under appropriate conditions. In a 20 acfm system, yellow phosphorous is oxidized to yield P.sub.2 O.sub.5 which picks up water to form H.sub.3 PO.sub.4 mists and can be collected as a valuable product. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50.degree. C. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO.sub.x and SO.sub.2, alkalis that are used for flue gas desulfurization are preferred. With this process, better than 90% of SO.sub.2 and NO in simulated flue gas can be removed. Stoichiometric ratios (P/NO) ranging between 0.6 and 1.5 were obtained.

  17. Gas diffusion electrode setup for catalyst testing in concentrated phosphoric acid at elevated temperatures.

    PubMed

    Wiberg, Gustav K H; Fleige, Michael; Arenz, Matthias

    2015-02-01

    We present a detailed description of the construction and testing of an electrochemical cell setup allowing the investigation of a gas diffusion electrode containing carbon supported high surface area catalysts. The setup is designed for measurements in concentrated phosphoric acid at elevated temperature, i.e., very close to the actual conditions in high temperature proton exchange membrane fuel cells (HT-PEMFCs). The cell consists of a stainless steel flow field and a PEEK plastic cell body comprising the electrochemical cell, which exhibits a three electrode configuration. The cell body and flow field are braced using a KF-25 vacuum flange clamp, which allows an easy assembly of the setup. As demonstrated, the setup can be used to investigate temperature dependent electrochemical processes on high surface area type electrocatalysts, but it also enables quick screening tests of HT-PEMFC catalysts under realistic conditions.

  18. Gas diffusion electrode setup for catalyst testing in concentrated phosphoric acid at elevated temperatures

    SciTech Connect

    Wiberg, Gustav K. H. E-mail: m.arenz@chem.ku.dk; Fleige, Michael; Arenz, Matthias E-mail: m.arenz@chem.ku.dk

    2015-02-15

    We present a detailed description of the construction and testing of an electrochemical cell setup allowing the investigation of a gas diffusion electrode containing carbon supported high surface area catalysts. The setup is designed for measurements in concentrated phosphoric acid at elevated temperature, i.e., very close to the actual conditions in high temperature proton exchange membrane fuel cells (HT-PEMFCs). The cell consists of a stainless steel flow field and a PEEK plastic cell body comprising the electrochemical cell, which exhibits a three electrode configuration. The cell body and flow field are braced using a KF-25 vacuum flange clamp, which allows an easy assembly of the setup. As demonstrated, the setup can be used to investigate temperature dependent electrochemical processes on high surface area type electrocatalysts, but it also enables quick screening tests of HT-PEMFC catalysts under realistic conditions.

  19. Fabrication of Alumina Nanowires from Porous Alumina Membranes by Etching in Phosphoric Acid Solution

    NASA Astrophysics Data System (ADS)

    Wang, Xuehua; Li, Chengyong; Ma, Lianjiao; Cao, Hong; Zhang, Baohua

    Alumina nanowires (ANWs) with high aspect ratios were synthesized by the chemical etching of porous alumina membranes (PAMs) in phosphoric acid solution. The morphology and structure of ANWs were analyzed by SEM and XRD, respectively. The results showed that the typical features of ANWs are around 35 nm in diameter and around 20 μm in length, the crystalline structure of the ANWs was amorphous, which was in accordance with that of the PAMs. Furthermore, the morphology of the PAMs was characterized by AFM and SEM in detail. On the basis of AFM and SEM observations, a possible formation mechanism of ANWs was discussed, and the inhomogeneous of the dissolution between the triple points and the side walls was considered to be the essential factor deciding the formation of ANWs.

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Preparation and evaluation of advanced electrocatalysts for phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Stonehart, P.; Baris, J.; Pagliaro, P.

    1980-09-01

    Results are presented for hydrogen oxidation and hydrogen oxidation poisoned by carbon monoxide at levels between 0 and 30%. Due to the high activities that are now being observed for our platinum based electrocatalysts, the hydrogen concentrations were reduced to 10% levels in the gas supplies. Perturbation techniques were used to determine that a mechanism for the efficient operation of our porous gas diffusion electrodes is diffusion of the carbon monoxide out of the electrode structure through the electrolyte film on the electro-catalyst. A survey of the literature on platinum group materials (PGM) was carried out so that an identification of successful electrocatalysts could be made. Two PGM electrocatalysts were prepared and performance data for hydrogen oxidation in hot phosphoric acid in the presence of high carbon monoxide concentrations showed that they matched the best platinum on carbon electrocatalysts but with an electrocatalyst cost that was half of the platinum catalyst cost.

  2. Preparation and evaluation of advanced electrocatalysts for phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Stonehart, P.; Baris, J.; Pagliaro, P.

    1980-01-01

    Results are presented for hydrogen oxidation and hydrogen oxidation poisoned by carbon monoxide at levels between 0 and 30%. Due to the high activities that are now being observed for our platinum based electrocatalysts, the hydrogen concentrations were reduced to 10% levels in the gas supplies. Perturbation techniques were used to determine that a mechanism for the efficient operation of our porous gas diffusion electrodes is diffusion of the carbon monoxide out of the electrode structure through the electrolyte film on the electro-catalyst. A survey of the literature on platinum group materials (PGM) was carried out so that an identification of successful electrocatalysts could be made. Two PGM electrocatalysts were prepared and performance data for hydrogen oxidation in hot phosphoric acid in the presence of high carbon monoxide concentrations showed that they matched the best platinum on carbon electrocatalysts but with an electrocatalyst cost that was half of the platinum catalyst cost.

  3. Evaluation of gas cooling for pressurized phosphoric acid fuel cell stacks

    NASA Technical Reports Server (NTRS)

    Farooque, M.; Skok, A. J.; Maru, H. C.; Kothmann, R. E.; Harry, R. W.

    1983-01-01

    Gas cooling is a more reliable, less expensive and a more simple alternative to conventional liquid cooling for heat removal from the phosphoric acid fuel cell (PAFC). The feasibility of gas cooling has already been demonstrated in atmospheric pressure stacks. This paper presents theoretical and experimental investigation of gas cooling for pressurized PAFC. Two approaches to gas cooling, Distributed Gas Cooling (DIGAS) and Separated Gas Cooling (SGC) were considered, and a theoretical comparison on the basis of cell performance indicated SGC to be superior to DIGAS. The feasibility of SGC was experimentally demonstrated by operating a 45-cell stack for 700 hours at pressure, and determining thermal response and the effect of other related parameters.

  4. Phosphoric acid pretreatment of Achyranthes aspera and Sida acuta weed biomass to improve enzymatic hydrolysis.

    PubMed

    Siripong, Premjet; Duangporn, Premjet; Takata, Eri; Tsutsumi, Yuji

    2016-03-01

    Achyranthes aspera and Sida acuta, two types of weed biomass are abundant and waste in Thailand. We focus on them as novel feedstock for bio-ethanol production because they contain high-cellulose content (45.9% and 46.9%, respectively) and unutilized material. Phosphoric acid (70%, 75%, and 80%) was employed for the pretreatment to improve by enzymatic hydrolysis. The pretreatment process removed most of the xylan and a part of the lignin from the weeds, while most of the glucan remained. The cellulose conversion to glucose was greater for pretreated A. aspera (86.2 ± 0.3%) than that of the pretreated S. acuta (82.2 ± 1.1%). Thus, the removal of hemicellulose significantly affected the efficiency of the enzymatic hydrolysis. The scanning electron microscopy images showed the exposed fibrous cellulose on the cell wall surface, and this substantial change of the surface structure contributed to improving the enzyme accessibility.

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

    SciTech Connect

    Uhrig, M.; Droste, W.; Wolf, D.

    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.

  6. Inertisation of galvanic sludge with calcium oxide, activated carbon, and phosphoric acid.

    PubMed

    Oreščanin, Višnja; Lovrenčić Mikelić, Ivanka; Kollar, Robert; Mikulić, Nenad; Medunić, Gordana

    2012-09-01

    In this study we compared three methods for the treatment of electroplating sludge highly loaded with zinc and iron: (1) calcium oxide-based solidification/stabilisation; (2) conversion into inert material by adsorption of organic and inorganic pollutants onto activated carbon; and (3) conversion of mobile waste components into insoluble phosphates. All three methods proved highly efficient in the conversion of hazardous waste into inert material. Under optimum treatment conditions zinc concentration in the leachate of solidified waste was reduced by 99.7 % compared to untreated sludge. Zinc retention efficiency in the waste treated with activated carbon and phosphoric acid was 99.9 % and 98.7 %, respectively. The advantages of electroplating sludge treatment with activated carbon over the other two methods are high sorption capacity, insignificant pH and volume changes of the sludge, and simple use.

  7. A neutron diffraction and computer modeling study of the interatomic structure of phosphoric acid

    NASA Astrophysics Data System (ADS)

    Tromp, R. Hans; Spieser, Stephane H.; Neilson, George W.

    1999-01-01

    Wide angle neutron diffraction in combination with H/D substitution was used to determine the inter- and intramolecular structure of 100% phosphoric acid (H3PO4, PA). From radial distribution functions gHH(r), gHX(r), and gXX(r) (where X is either O or P) the hydrogen bonds were found to be characterized by a very short O…H distance (1.54 Å). Within a molecule, the orientation of an OH group was found to be preferably in one of the three O-P-O planes. In the interpretation of the radial distribution functions, use was made of preliminary results of molecular dynamics simulations. Temperature effects on the structure of PA were only found in the hydrogen bond structure, which becomes somewhat less well defined when heating up from room temperature to 60 °C. Polyphosphates could not be detected, probably due to the small degree of polymerization.

  8. Evaluation of gas cooling for pressurized phosphoric acid fuel cell stacks

    NASA Technical Reports Server (NTRS)

    Farooque, M.; Skok, A. J.; Maru, H. C.; Kothmann, R. E.; Harry, R. W.

    1983-01-01

    Gas cooling is a more reliable, less expensive and a more simple alternative to conventional liquid cooling for heat removal from the phosphoric acid fuel cell (PAFC). The feasibility of gas cooling has already been demonstrated in atmospheric pressure stacks. This paper presents theoretical and experimental investigation of gas cooling for pressurized PAFC. Two approaches to gas cooling, Distributed Gas Cooling (DIGAS) and Separated Gas Cooling (SGC) were considered, and a theoretical comparison on the basis of cell performance indicated SGC to be superior to DIGAS. The feasibility of SGC was experimentally demonstrated by operating a 45-cell stack for 700 hours at pressure, and determining thermal response and the effect of other related parameters.

  9. Porous texture of activated carbons prepared by phosphoric acid activation of woods

    NASA Astrophysics Data System (ADS)

    Díaz-Díez, M. A.; Gómez-Serrano, V.; Fernández González, C.; Cuerda-Correa, E. M.; Macías-García, A.

    2004-11-01

    Activated carbons (ACs) have been prepared using chestnut, cedar and walnut wood shavings from furniture industries located in the Comunidad Autónoma de Extremadura (SW Spain). Phosphoric acid (H3PO4) at different concentrations (i.e. 36 and 85 wt.%) has been used as activating agent. ACs have been characterized from the results obtained by N2 adsorption at 77 K. Moreover, the fractal dimension (D) has been calculated in order to determine the AC surface roughness degree. Optimal textural properties of ACs have been obtained by chemical activation with H3PO4 36 wt.%. This is corroborated by the slightly lower values of D for samples treated with H3PO4 85 wt.%.

  10. Asymmetric Arylative Dearomatization of β-Naphthols Catalyzed by a Chiral Phosphoric Acid.

    PubMed

    Li, Xiao-Qiang; Yang, Hui; Wang, Jiao-Jiao; Gou, Bo-Bo; Chen, Jie; Zhou, Ling

    2017-04-19

    An enantioselective arylative dearomatization reaction of β-naphthols with quinone monoimides has been developed for the first time using a chiral phosphoric acid as the catalyst, the desired enantioenriched cyclohexadienones were prepared with excellent yields and enantioselectivities by a domino Michael addition and aromatization process (up to 99 % yield, up to 98 % ee). This process is operationally simple and readily scaled up, as well as a broad substrate scope which includes 1-substituted-2-naphthols with/without 3-substituents. Furthermore, this organocatalytic procedure allows the lowering of catalyst loading to 0.5 mol % without considerable loss in reactivity and enantioselectivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Method for the purification of bis (2-ethyl-hexyl)phosphoric acid

    DOEpatents

    Schulz, W.W.

    1974-02-19

    Foreign products including the neutral organophosphorous compounds and the iron salts normally present in commercial bis(2ethyl-hexyl) phosphoric acid(HDEHP), and the radiolytic degradation products of HDEHP on exposure of HDEHP to beta and gamma irradiation are removed from HDEHP containing one or more of such products by contacting the said foreign product containing HDEHP with a macroreticular anion exchange resin in base form whereby the DEHP- ion of HDEHP exchanges with the anion of the resin and is thus adsorbed on the resin and the said foreign products are not adsorbed and will pass through a bed of particles of the resin. The adsorbed DEHP- ion is then eluted from the resin and acidified to form and recover the purified HDEHP. (auth)

  12. Evaluation of Gas-Cooled Pressurized Phosphoric Acid Fuel Cells for Electric Utility Power Generation

    NASA Technical Reports Server (NTRS)

    Faroque, M.

    1983-01-01

    Gas cooling is a more reliable, less expensive and a more simple alternative to conventional liquid cooling for heat removal from the phosphoric acid fuel cell (PAFC). The feasibility of gas-cooling was already demonstrated in atmospheric pressure stacks. Theoretical and experimental investigations of gas-cooling for pressurized PAFC are presented. Two approaches to gas cooling, Distributed Gas-Cooling (DIGAS) and Separated Gas-Cooling (SGC) were considered, and a theoretical comparison on the basis of cell performance indicated SGC to be superior to DIGAS. The feasibility of SGC was experimentally demonstrated by operating a 45-cell stack for 700 hours at pressure, and determining thermal response and the effect of other related parameters.

  13. Gas diffusion electrode setup for catalyst testing in concentrated phosphoric acid at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Wiberg, Gustav K. H.; Fleige, Michael; Arenz, Matthias

    2015-02-01

    We present a detailed description of the construction and testing of an electrochemical cell setup allowing the investigation of a gas diffusion electrode containing carbon supported high surface area catalysts. The setup is designed for measurements in concentrated phosphoric acid at elevated temperature, i.e., very close to the actual conditions in high temperature proton exchange membrane fuel cells (HT-PEMFCs). The cell consists of a stainless steel flow field and a PEEK plastic cell body comprising the electrochemical cell, which exhibits a three electrode configuration. The cell body and flow field are braced using a KF-25 vacuum flange clamp, which allows an easy assembly of the setup. As demonstrated, the setup can be used to investigate temperature dependent electrochemical processes on high surface area type electrocatalysts, but it also enables quick screening tests of HT-PEMFC catalysts under realistic conditions.

  14. Edge-Functionalization of Pyrene as a Miniature Graphene via Friedel-Crafts Acylation Reaction in Poly(Phosphoric Acid)

    NASA Astrophysics Data System (ADS)

    Jeon, In-Yup; Choi, Eun-Kyoung; Bae, Seo-Yoon; Baek, Jong-Beom

    2010-10-01

    The feasibility of edge-functionalization of graphite was tested via the model reaction between pyrene and 4-(2,4,6-trimethylphenyloxy)benzamide (TMPBA) in poly(phosphoric acid) (PPA)/phosphorous pentoxide (P2O5) medium. The functionalization was confirmed by various characterization techniques. On the basis of the model study, the reaction condition could be extended to the edge-functionalization of graphite with TMPBA. Preliminary results showed that the resultant TMPBA-grafted graphite (graphite-g-TMPBA) was found to be readily dispersible in N-methyl-2-pyrrolidone (NMP) and can be used as a precursor for edge-functionalized graphene (EFG).

  15. Effect of phosphoric acid pretreatment on enzymatic hydrolysis of microcrystalline cellulose.

    PubMed

    Zhang, Juanhua; Zhang, Beixiao; Zhang, Jingqiang; Lin, Lu; Liu, Shijie; Ouyang, Pingkai

    2010-01-01

    Microcrystalline cellulose (MCC) was pretreated with phosphoric acid at 323K for 10h. X-ray diffraction (XRD) and Atomic Force Microscope (AFM) analyses revealed that the fiber surface morphology of pretreated MCC (P-MCC) were uneven and rough with the crystalline diffraction peaks of P-MCC decreased to a distinct range. The X-ray Photoelectron Spectroscopy (XPS) analysis showed that the uneven and rough surface of P-MCC could enhance the adsorption of cellulose to the molecular surface of cellulose, which is one of the key factors affecting enzymatic hydrolysis of cellulose. A reversible first order kinetics was employed to describe the adsorption kinetics of cellulase to MCC and P-MCC, and the adsorption rate constants of MCC and P-MCC were found to be 0.016, 0.024, 0.041, and 0.095, 0.149, 0.218min(-1), respectively at 278K, 293K and 308K. The activation energies of MCC and P-MCC hydrolysis reactions were found to be 22.257 and 19.721kJ mol(-1). The major hydrolysis products of MCC and P-MCC were cellobiose and glucose. Hydrolysis of MCC for 120h resulted in yields of glucose (7.21%), cellobiose (13.16%) and total sugars (20.37%). However, after the pretreatment with phosphoric acid, the corresponding sugar yields resulted from enzymatic hydrolysis of P-MCC were increased to 24.10%, 41.42%, and 65.52%; respectively, which were 3.34, 3.15, and 3.22 times of the sugars yields from enzymatic hydrolysis of MCC.

  16. Utilization of date stones for production of activated carbon using phosphoric acid

    SciTech Connect

    Haimour, N.M. . E-mail: nomanhaimour@hotmail.com; Emeish, S. . E-mail: s_emiesh@yahoo.com

    2006-07-01

    Date stone wastes have been utilized for production of activated carbon by chemical activation with phosphoric acid using a fluidized-bed reactor. The effects of the activation time, activation temperature, impregnation ratio, and particle size on the yield and the adsorptive capacity towards iodine were studied. The yield and the quality of the activated carbon prepared by using H{sub 3}PO{sub 4} were compared with that prepared from date stones using the same equipment, and under similar conditions by using ZnCl{sub 2} as an oxidizing agent. The maximum value of the iodine number of the activated carbon produced using H{sub 3}PO{sub 4} in this work was about 495 under the following conditions: impregnation ratio 0.4, activation time 60 min, activation temperature 800 deg. C, particle size 0.60 mm. The iodine number for the produced activated carbon was higher when phosphoric acid was used, compared to that when zinc chloride was used as impregnation reagent; however, the yield obtained when H{sub 3}PO{sub 4} was used was lower than the yield when ZnCl{sub 2} was used. The iodine number increases significantly with increasing the activation temperature. By increasing the impregnation ratio at the same temperature, the iodine number decreased sharply and an oscillation is noticed for all the cases but it was clearer at 800 deg. C. The average variation of the iodine number for the whole range of particle size used in this work is {+-}10%.

  17. Enamel roughness and depth profile after phosphoric acid etching of healthy and fluorotic enamel.

    PubMed

    Torres-Gallegos, I; Zavala-Alonso, V; Patiño-Marín, N; Martinez-Castañon, G A; Anusavice, K; Loyola-Rodríguez, J P

    2012-06-01

    Dental fluorosis requires aesthetic treatment to improve appearance and etching of enamel surfaces with phosphoric acid is a key step for adhesive restorations. The aim of this study was to evaluate surface roughness and a depth profile in healthy and fluorotic enamel before and after phosphoric acid etching at 15, 30 and 60 seconds. One hundred and sixty enamel samples from third molars with no fluorosis to severe fluorosis were evaluated by atomic force microscopy. Healthy enamel showed a statistically significant difference (p < 0.05) between mean surface roughness at 15 seconds (180.3 nm), 30 seconds (260.9 nm) and 60 seconds (346.5 nm); depth profiles revealed a significant difference for the 60 second treatment (4240.2 nm). For mild fluorosis, there was a statistically significant difference (p < 0.05) between mean surface roughness for 30 second (307.8 nm) and 60 second (346.6 nm) treatments; differences in depth profiles were statistically significant at 15 seconds (2546.7 nm), 30 seconds (3884.2 nm) and 60 seconds (3612.1 nm). For moderate fluorosis, a statistically significant difference (p < 0.05) was observed for surface roughness for 30 second (324.5 nm) and 60 second (396.6 nm) treatments. Surface roughness and depth profile analyses revealed that the best etching results were obtained at 15 seconds for the no fluorosis and mild fluorosis groups, and at 30 seconds for the moderate fluorosis group. Increasing the etching time for severe fluorosis decreased surface roughness and the depth profile, which suggests less micromechanical enamel retention for adhesive bonding applications. © 2012 Australian Dental Association.

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

    PubMed

    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.

  19. Spatial variability of soil carbon, pH, available phosphorous and potassium in organic farm located in Mediterranean Croatia

    NASA Astrophysics Data System (ADS)

    Bogunović, Igor; Pereira, Paulo; Šeput, Miranda

    2016-04-01

    Soil organic carbon (SOC), pH, available phosphorus (P), and potassium (K) are some of the most important factors to soil fertility. These soil parameters are highly variable in space and time, with implications to crop production. The aim of this work is study the spatial variability of SOC, pH, P and K in an organic farm located in river Rasa valley (Croatia). A regular grid (100 x 100 m) was designed and 182 samples were collected on Silty Clay Loam soil. P, K and SOC showed moderate heterogeneity with coefficient of variation (CV) of 21.6%, 32.8% and 51.9%, respectively. Soil pH record low spatial variability with CV of 1.5%. Soil pH, P and SOC did not follow normal distribution. Only after a Box-Cox transformation, data respected the normality requirements. Directional exponential models were the best fitted and used to describe spatial autocorrelation. Soil pH, P and SOC showed strong spatial dependence with nugget to sill ratio with 13.78%, 0.00% and 20.29%, respectively. Only K recorded moderate spatial dependence. Semivariogram ranges indicate that future sampling interval could be 150 - 200 m in order to reduce sampling costs. Fourteen different interpolation models for mapping soil properties were tested. The method with lowest Root Mean Square Error was the most appropriated to map the variable. The results showed that radial basis function models (Spline with Tension and Completely Regularized Spline) for P and K were the best predictors, while Thin Plate Spline and inverse distance weighting models were the least accurate. The best interpolator for pH and SOC was the local polynomial with the power of 1, while the least accurate were Thin Plate Spline. According to soil nutrient maps investigated area record very rich supply with K while P supply was insufficient on largest part of area. Soil pH maps showed mostly neutral reaction while individual parts of alkaline soil indicate the possibility of penetration of seawater and salt accumulation in the

  20. Multinuclear NMR study of the effect of acid concentration on ion transport in phosphoric acid doped poly(benzimidazole) membranes.

    PubMed

    Suarez, Sophia; Kodiweera, N K A C; Stallworth, P; Yu, Seonghan; Greenbaum, S G; Benicewicz, B C

    2012-10-18

    (1)H and (31)P NMR spectra, line widths, spin-lattice relaxation times (T(1)), and (1)H self-diffusion coefficients (D) were determined for two distinct poly(benzimidazole) (PBI) proton exchange membranes (PEM), para-PBI and dihydroxy-PBI (2OH-PBI), both incorporating varying concentrations of phosphoric acid. The study was performed over the temperature range of 20-180 °C, for phosphoric acid concentrations of 30, 50, and 70 wt %. Of the two samples, less mobility was indicated for the 2OH-PBI compared with the para-PBI at all acid concentrations. It was also observed that increasing the acid content resulted in an increase in the temperature at which the T(1) minimum or plateau occurred. (31)P spectra reveal the presence of pyrophosphates and in the case of the 50 and 70 wt % para-PBI samples higher oligomers such as tripolyphosphates. (1)H D data showed the 30 wt % para-PBI having almost identical values as the 70 wt % 2OH-PBI over the entire temperature range. In general, stronger short- and long-range interactions were observed in the 2OH-PBI matrix, yielding reduced translational proton transport compared to that of para-PBI. While these stronger interactions hinder translational proton diffusion, they could enhance proton transport by the Grotthuss or structure diffusion mechanism, the more favorable transport mechanism. Activation energies obtained from the (1)H D data supports a proton-hopping mechanism, with possible assistance from fast exchange between phosphate groups.

  1. Decalcifying effect of 15% EDTA, 15% citric acid, 5% phosphoric acid and 2.5% sodium hypochlorite on root canal dentine.

    PubMed

    Pérez-Heredia, M; Ferrer-Luque, C M; González-Rodríguez, M P; Martín-Peinado, F J; González-López, S

    2008-05-01

    To evaluate and compare ex vivo the decalcifying effect of 15% EDTA, 15% citric acid, 5% phosphoric acid and 2.5% sodium hypochlorite on root canal dentine. Two 2-mm-thick slices were cut from the coronal third of the root of 10 human incisors. Each slice was sectioned into two equal parts. Specimens were assigned to one of four groups (n = 10) for immersion in 20 mL of either 15% EDTA, or 15% citric acid, 5% phosphoric acid or 2.5% NaOCl, for three time periods (5, 10 and 15 min). The concentration of Ca(2+) extracted from the dentine was measured by atomic absorption spectrophometry. The amount of calcium extracted was analysed using the Kruskal-Wallis test for global comparisons and the Mann-Whitney U-test for pairwise comparisons. In the three time periods, 15% EDTA and 15% citric acid extracted the largest amount of calcium, with no significant differences between them. The 2.5% NaOCl solution extracted insignificant amounts of calcium, whereas 15% EDTA extracted 86.72% of the calcium in the first 5 min, and 15% citric acid and 5% phosphoric acid had a similar pattern of calcium removal (77.03% and 67.08% in first 5 min, respectively). Solutions of 15% EDTA, 15% citric acid and 5% phosphoric acid decalcify root dentine, with most calcium extracted during the first 5 min of action. The efficacy of 15% citric acid and 15% EDTA solutions was significantly greater than that of 5% phosphoric acid solution at each time period (5, 10 and 15 min).

  2. Tissue-specific regulation of potassium homeostasis by high doses of cationic amino acids.

    PubMed

    Cremades, Asunción; Del Rio-Garcia, Jesús; Lambertos, Ana; López-Garcia, Carlos; Peñafiel, Rafael

    2016-01-01

    The administration of l-arginine hydrochloride has been used for testing pituitary secretion in humans, and as an experimental model for induction of acute pancreatitis in rats and mice. Whereas in the first case, the administration of the amino acid is associated with hiperkalemia, in the model of acute pancreatitis no data are available on possible changes in potassium homeostasis. The present study shows that the acute administration to mice of l-arginine hydrochloride or other cationic amino acids almost duplicate plasma potassium levels. This effect was associated to a marked decrease of tissue potassium in both pancreas and liver. No changes were found in other tissues. These changes cannot be ascribed to the large load of chloride ions, since similar effects were produced when l-ornithine aspartate was administered. The changes in potassium levels were dependent on the dose. The displacement of intracellular potassium from the liver and pancreas to the extracellular compartment appears to be dependent on the entry of the cationic amino acid, since the administration of an equivalent dose of alfa-difluoromethyl ornithine HCl (DFMO), a non physiological analog of l-ornithine, which is poorly taken by the tissues in comparison with the physiological cationic amino acids, did not produce any change in potassium levels in pancreas and liver. The analyses of the expression of cationic amino acid transporters (CAT) suggest that the CAT-2 transporter may be implicated in the potassium/cationic amino acid interchange in liver and pancreas. The possible physiological or pathological relevance of these findings is discussed.

  3. A Comparative Study of Phosphoric Acid-doped m-PBI Membranes

    SciTech Connect

    Perry, Kelly A; More, Karren Leslie; Payzant, E Andrew; Meisner, Roberta A; Sumpter, Bobby G; Benicewicz, Brian

    2014-01-01

    Phosphoric acid (PA)-doped m-polybenzimidazole (PBI) membranes used in high temperature fuel cells and hydrogen pumps were prepared by a conventional imbibing process and a sol-gel fabrication process. A comparative study was conducted to investigate the critical properties of PA doping levels, ionic conductivities, mechanical properties, and molecular ordering. This systematic study found that sol-gel PA-doped m-PBI membranes were able to absorb higher acid doping levels and to achieve higher ionic conductivities than conventionally imbibed membranes when treated in an equivalent manner. Even at similar acid loadings, the sol-gel membranes exhibited higher ionic conductivities. Heat treatment of conventionally imbibed membranes with 29wt% solids caused a significant reduction in mechanical properties; conversely, sol-gel membranes exhibited an enhancement in mechanical properties. From X-ray structural studies and atomistic simulations, both conventionally imbibed and sol-gel membranes exhibited d-spacings of 3.5 and 4.6 , which were tentatively attributed to parallel ring stacking and staggered side-to-side packing, respectively, of the imidazole rings in these aromatic hetercyclic polymers. An anisotropic staggered side-to-side chain packing present in the conventional membranes may be root to the reduction in mechanical properties.

  4. Enhanced proton conductivity of Nafion composite membrane by incorporating phosphoric acid-loaded covalent organic framework

    NASA Astrophysics Data System (ADS)

    Yin, Yongheng; Li, Zhen; Yang, Xin; Cao, Li; Wang, Chongbin; Zhang, Bei; Wu, Hong; Jiang, Zhongyi

    2016-11-01

    Design and fabrication of efficient proton transport channels within solid electrolytes is crucial and challenging to new energy-relevant devices such as proton exchange membrane fuel cells (PEMFCs). In this study, the phosphoric acid (H3PO4) molecules are impregnated into SNW-1-type covalent organic frameworks (COFs) via vacuum assisted method. High loading of H3PO4 in SNW-1 and low guest leaching rate are achieved due to the similar diameter between H3PO4 and micropores in SNW-1. Then the COF-based composite membranes are fabricated for the first time with impregnated COFs (H3PO4@SNW-1) and Nafion matrix. For the composite membranes, the acid-base pairs formed between H3PO4@SNW-1 networks and Nafion optimize the interfacial interactions and hydrophilic domains. The acidic -PO3H2 groups in pores of H3PO4@SNW-1 provide abundant proton transfer sites. As a result, the continuous proton transfer channels with low energy barrier are created. At the filler content of 15 wt%, the composite membrane exhibits a superior proton conductivity of 0.0604 S cm-1 at 51% relative humidity and 80 °C. At the same time, the maximum power density of single fuel cell is 60.3% higher than that of the recast Nafion membrane.

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

    PubMed

    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.

  6. The effects of excess phosphoric acid in a Polybenzimidazole-based high temperature proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Matar, Saif; Higier, Andrew; Liu, Hongtan

    A series of experiments are conducted in order to investigate the performance of a proton exchange membrane (PEM) fuel cell using a commercially available polybenzimidazole (PBI)-based high temperature membrane. During the study a drastic degradation in performance is observed over time and a significant amount of solid material built-up is found in the flow field plate and the membrane-electrode assembly (MEA). The built-up material is examined by the use of a Scanning Electron Microscope (SEM). Further elemental analysis using Energy Dispersive X-ray Spectroscopy (EDS) finds that the built-up material contains large amount of phosphorus, thus relating it with the excess phosphoric acid found in the MEA. Additional experimental studies show that the built-up material is caused by the excess acid solution in the MEA, and when the excess phosphoric acid is removed from the MEA the fuel cell performance improves significantly and becomes very stable.

  7. Naturally occurring radioactive material (NORM) from a former phosphoric acid processing plant.

    PubMed

    Beddow, H; Black, S; Read, D

    2006-01-01

    In recent years there has been an increasing awareness of the radiological impact of non-nuclear industries that extract and/or process ores and minerals containing naturally occurring radioactive material (NORM). These industrial activities may result in significant radioactive contamination of (by-) products, wastes and plant installations. In this study, scale samples were collected from a decommissioned phosphoric acid processing plant. To determine the nature and concentration of NORM retained in pipe-work and associated process plant, four main areas of the site were investigated: (1) the 'Green Acid Plant', where crude acid was concentrated; (2) the green acid storage tanks; (3) the Purified White Acid (PWA) plant, where inorganic impurities were removed; and (4) the solid waste, disposed of on-site as landfill. The scale samples predominantly comprise the following: fluorides (e.g. ralstonite); calcium sulphate (e.g. gypsum); and an assemblage of mixed fluorides and phosphates (e.g. iron fluoride hydrate, calcium phosphate), respectively. The radioactive inventory is dominated by 238U and its decay chain products, and significant fractionation along the series occurs. Compared to the feedstock ore, elevated concentrations (< or =8.8 Bq/g) of 238U were found to be retained in installations where the process stream was rich in fluorides and phosphates. In addition, enriched levels (< or =11 Bq/g) of 226Ra were found in association with precipitates of calcium sulphate. Water extraction tests indicate that many of the scales and waste contain significantly soluble materials and readily release radioactivity into solution.

  8. Amended safety assessment of tall oil acid, sodium tallate, potassium tallate, and ammonium tallate.

    PubMed

    Robinson, Valerie; Bergfeld, Wilma F; Belsito, Donald V; Klaassen, Curtis D; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Alan Andersen, F

    2009-01-01

    Tall oil acid is a mixture of oleic and linoleic acids (fatty acids) and rosin acids derived from tall oil, a by-product of pulp from resinous woods, used in cosmetic products as a surfactant at concentrations up to 8%. Ammonium, potassium, and sodium salts also are listed as cosmetic ingredients. In addition to the studies summarized in this report, extensive toxicity, genotoxicity, and carcinogenicity studies in animals are available for oleic, lauric, palmitic, myristic, and stearic fatty acids as published earlier by the Cosmetic Ingredient Review (CIR). These data may be extrapolated to tall oil acid and its salts. There are no reports of current uses or use concentration data for ammonium tallate, nor are use concentration data available for the other salts. The CIR Expert Panel found tall oil acid, ammonium tallate, potassium tallate, and sodium tallate to be safe cosmetic ingredients in the given practices of use and concentration.

  9. Low dietary potassium intakes and high dietary estimates of net endogenous acid production are associated with low bone mineral density in premenopausal women and increased markers of bone resorption in postmenopausal women.

    PubMed

    Macdonald, Helen M; New, Susan A; Fraser, William D; Campbell, Marion K; Reid, David M

    2005-04-01

    The Western diet may be a risk factor for osteoporosis. Excess acid generated from high protein intakes increases calcium excretion and bone resorption. Fruit and vegetable intake could balance this excess acidity by providing alkaline salts of potassium. Algorithms based on dietary intakes of key nutrients can be used to approximate net endogenous acid production (NEAP) and to explore the association between dietary acidity and bone health. We investigated the relation between dietary potassium and protein, NEAP (with an algorithm including the ratio of protein to potassium intake), and potential renal acid load (with an algorithm including dietary protein, phosphorous, potassium, magnesium, and calcium) and markers of bone health. Measurements of bone mineral density (BMD) (n = 3226) and urinary bone resorption markers (n = 2929) at the lumbar spine and femoral neck were performed in perimenopausal and early postmenopausal women aged 54.9 +/- 2.2 y (x +/- SD) in 1997-1999. BMD (g/cm(2)), free pyridinoline (fPYD), and free deoxypyridinoline (fDPD) were expressed relative to creatinine. Dietary intake was assessed with a food-frequency questionnaire. Comparison of the highest with the lowest quartile of potassium intake or the lowest with the highest NEAP showed a 6-8% increase in fPYD/creatinine and fDPD/creatinine. A difference of 8% in BMD was observed between the highest and lowest quartiles of potassium intake in the premenopausal group (n = 337). Dietary potassium, an indicator of NEAP and fruit and vegetable intake, may exert a modest influence on markers of bone health, which over a lifetime may contribute to a decreased risk of osteoporosis.

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

    NASA Astrophysics Data System (ADS)

    Nores-Pondal, Federico J.; Buera, M. Pilar; Corti, Horacio R.

    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 3PO 4-H 2O 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.

  11. Effect of Phosphoric Acid on the Degradation of Human Dentin Matrix

    PubMed Central

    Tezvergil-Mutluay, A.; Mutluay, M.; Seseogullari-Dirihan, R.; Agee, K.A.; Key, W.O.; Scheffel, D.L.S.; Breschi, L.; Mazzoni, A.; Tjäderhane, L.; Nishitani, Y.; Tay, F.R.; Pashley, D.H.

    2013-01-01

    This study determined if dentin proteases are denatured by phosphoric acid (PA) used in etch-and-rinse dentin adhesives. Dentin beams were completely demineralized with EDTA for 30 days. We “acid-etched” experimental groups by exposing the demineralized dentin beams to 1, 10, or 37 mass% PA for 15 sec or 15 min. Control beams were not exposed to PA but were incubated in simulated body fluid for 3 days to assay their total endogenous telopeptidase activity, by their ability to solubilize C-terminal crosslinked telopeptides ICTP and CTX from insoluble dentin collagen. Control beams released 6.1 ± 0.8 ng ICTP and 0.6 ± 0.1 ng CTX/mg dry-wt/3 days. Positive control beams pre-incubated in p-aminophenylmercuric acetate, a compound known to activate proMMPs, released about the same amount of ICTP peptides, but released significantly less CTX. Beams immersed in 1, 10, or 37 mass% PA for 15 sec or 15 min released amounts of ICTP and CTX similar to that released by the controls (p > 0.05). Beams incubated in galardin, an MMP inhibitor, or E-64, a cathepsin inhibitor, blocked most of the release of ICTP and CTX, respectively. It is concluded that PA does not denature endogenous MMP and cathepsin activities of dentin matrices. PMID:23103634

  12. An investigation of Pt alloy oxygen reduction catalysts in phosphoric acid doped PBI fuel cells

    NASA Astrophysics Data System (ADS)

    Mamlouk, M.; Scott, K.

    A study of a phosphoric acid doped polybenzimidazole (PBI) membrane fuel cell using commercial carbon supported, Pt alloy oxygen reduction catalysts is reported. The cathodes were made from PTFE bonded carbon supported Pt alloys without PBI but with phopshoric acid added to the electrode for ionic conductivity. Polarisation data for fuel cells with cathodes made with alloys of Pt with Ni, Co, Ru and Fe are compared with those with Pt alone as cathode at temperatures between 120 and 175 °C. With the same loading of Pt enhancement in cell performance was achieved with all alloys except Pt-Ru, in the low current density activation kinetics region of operation. The extent of enhancement depended upon the operating temperature and also the catalyst loading. In particular a Pt-Co alloy produced performance significantly better than Pt alone, e.g. a peak power, with low pressure air, of 0.25 W cm -2 with 0.2 mg Pt cm -2 of a 20 wt% Pt-Co catalyst.

  13. Mechanistic insights into a BINOL-derived phosphoric acid-catalyzed asymmetric Pictet-Spengler reaction.

    PubMed

    Overvoorde, Lois M; Grayson, Matthew N; Luo, Yi; Goodman, Jonathan M

    2015-03-06

    The reaction of tryptamine and (2-oxocyclohexyl)acetic acid can be catalyzed by 3,3'-bis(triphenylsilyl)-1,1'-bi-2-naphthol phosphoric acid to give an asymmetric β-carboline. This reaction was first studied by Holloway et al. ( Org. Lett. 2010 , 12 , 4720 - 4723 ), but their mechanistic work did not explain the high stereoselectivity achieved. This study uses density functional theory and hybrid quantum mechanics/molecular mechanics calculations to investigate this reaction and provide a model to explain its outcome. The step leading to diastereo- and enantioselectivity is an asymmetric Pictet-Spengler reaction involving an N-acyliminium ion bound to the catalyst in a bidentate fashion. This interaction occurs via hydrogen bonds between the two terminal oxygen atoms of the catalyst phosphate group and the hydrogen atoms at N and C2 of the substrate indole group. These bonds hold the transition structure rigidly and thus allow the catalyst triphenylsilyl groups to influence the enantioselectivity.

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

    PubMed

    Cao, Xinde; Wahbi, Ammar; Ma, Lena; Li, Bing; Yang, Yongliang

    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(3)PO(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(3)PO(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.

  15. Enantiodivergent Atroposelective Synthesis of Chiral Biaryls by Asymmetric Transfer Hydrogenation: Chiral Phosphoric Acid Catalyzed Dynamic Kinetic Resolution.

    PubMed

    Mori, Keiji; Itakura, Tsubasa; Akiyama, Takahiko

    2016-09-12

    Reported herein is an enantiodivergent synthesis of chiral biaryls by a chiral phosphoric acid catalyzed asymmetric transfer hydrogenation reaction. Upon treatment of biaryl lactols with aromatic amines and a Hantzsch ester in the presence of chiral phosphoric acid, dynamic kinetic resolution (DKR) involving a reductive amination reaction proceeded smoothly to furnish both R and S isomers of chiral biaryls with excellent enantioselectivities by proper choice of hydroxyaniline derivative. This trend was observed in wide variety of substrates, and various chiral biphenyl and phenyl naphthyl adducts were synthesized with satisfactory enantioselectivities in enantiodivergent fashion. The enantiodivergent synthesis of synthetically challenging, chiral o-tetrasubstituted biaryls were also accomplished, and suggests high synthetic potential of the present method.

  16. Non-aqueous gel polymer electrolyte with phosphoric acid ester and its application for quasi solid-state supercapacitors

    NASA Astrophysics Data System (ADS)

    Łatoszyńska, Anna A.; Żukowska, Grażyna Zofia; Rutkowska, Iwona A.; Taberna, Pierre-Louis; Simon, Patrice; Kulesza, Pawel J.; Wieczorek, Władysław

    2015-01-01

    A mechanically-stable non-aqueous proton-conducting gel polymer electrolyte that is based on methacrylate monomers, is considered here for application in solid-state type supercapacitors. An electrochemical cell using activated carbon as active materials and the new gel polymer electrolyte has been characterized at room temperature using cyclic voltammetry, galvanostatic charge-discharge cycle tests as well as impedance spectroscopy. The use of phosphoric acid ester (instead of phosphoric acid) as a proton donor has led to an increase of both the operation voltage window (up to 1.3 V) and the electrolyte ionic conductivity (on the level of an order of magnitude). The resulting double layer capacitance of the microporous activated carbon was found to be as high as 120 F g-1; even more important, the supercapacitor utilizing non-aqueous proton-conducting gel polymer electrolyte is well-behaved in the wide temperature range (namely, from -40 to 80 °C).

  17. Purification of industrial phosphoric acid (54 %) using Fe-pillared bentonite.

    PubMed

    Hamza, Wiem; Chtara, Chaker; Benzina, Mourad

    2016-08-01

    The current problem of excess impurities in industrial phosphoric acid (IPA) 54 % P2O5 makes phosphates industries look toward low-cost but efficient adsorbents. In the present study, iron-oxide-modified bentonite (Fe-PILB) was prepared and investigated as a possible adsorbent for the removal of organic matter (OM) like humic acid (HA), chromium (Cr(III)), and zinc (Zn(II)) from IPA aqueous solutions. These adsorbents were characterized using XRD, TEM, and BET. The adsorption of impurities is well described by the pseudo-second-order model. The results indicate that Fe-PILB has a good ability to resist co-existing anions and the low-pH condition of IPA and owns a relatively high-removal capacity of 80.42 and 25 % for OM, Cr(III), and Zn(II). The mechanism of adsorption may be described by the ligand and ion exchange that happened on the active sites. The selected order of adsorption OM > Cr(3+) > Zn(2+) showed the importance of the competitive phenomenon onto bentonite materials' pore adsorption. For the adsorption of OM at the low pH of IPA, H-bond complexation was the dominant mechanism. From the adsorption of heavy metals and OM complex compounds contained in IPA 54 % on Fe-PILB, the bridging of humic acid between bentonite and heavy metals (Zn(II) or Cr(III)) is proposed as the dominant adsorption mechanism (bentonite-HA-Me). Overall, the results obtained in this study indicate Fe-pillared bentonite possesses a potential for the practical application of impurity (OM, Zn(II), and Cr(III)) removal from IPA aqueous solutions.

  18. Chiral Phosphoric Acid-Catalyzed Enantioselective Reductive Amination of 2-Pyridyl Ketones: Construction of Structurally Chiral Pyridine-Based Ligands.

    PubMed

    Abudu Rexit, Abulikemu; Luo, Shiwei; Mailikezati, Maihemuti

    2016-11-18

    A chiral phosphoric acid-catalyzed one-pot enantioselective reductive amination of 2-pyridyl ketones was realized to provide chiral pyridine-based ligands in excellent yields with high enantioselectivities (up to 98% yield, 94% ee). Computational studies on the key intermediate imine and transition state of the hydride transfer process revealed that the nitrogen atom of the pyridyl ring might be an important factor to significantly promote both the reaction activity and enantioselectivity.

  19. Oxidation kinetics of crystal violet by potassium permanganate in acidic medium

    NASA Astrophysics Data System (ADS)

    Khan, Sameera Razi; Ashfaq, Maria; Mubashir; Masood, Summyia

    2016-05-01

    The oxidation kinetics of crystal violet (a triphenylmethane dye) by potassium permanganate was focused in an acidic medium by the spectrophotometric method at 584 nm. The oxidation reaction of crystal violet by potassium permanganate is carried out in an acidic medium at different temperatures ranging within 298-318 K. The kinetic study was carried out to investigate the effect of the concentration, ionic strength and temperature. The reaction followed first order kinetics with respect to potassium permanganate and crystal violet and the overall rate of the reaction was found to be second order. Thermodynamic activation parameters like the activation energy ( E a), enthalpy change (Δ H*), free energy change (Δ G*), and entropy change (Δ S*) have also been evaluated.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Fluoride removal from groundwater by limestone treatment in presence of phosphoric acid.

    PubMed

    Gogoi, Sweety; Nath, Suresh K; Bordoloi, Shreemoyee; Dutta, Robin K

    2015-04-01

    Fluoride removal from groundwater has been studied by addition of dilute phosphoric acid (PA) to the influent water before limestone treatment through laboratory plug-flow column experiments and bench-scale plug-flow pilot tests. In this PA-enhanced limestone defluoridation (PAELD) technique, fluoride is removed from 0.526 mM to 0.50-52.60 μM in 3 h with near neutral final pH. The presence of PA increases the fluoride removal capacity of limestone to 1.10 mg/g compared to 0.39 mg/g reported in its absence. The changes in fluoride removal with variation in initial PA concentration, initial fluoride concentration and the final pH have been found to be statistically significant with p < 0.05. The estimated recurring cost is US$ ≈0.58/m(3) water. Simple scrubbing and rinsing is a preferable method for regeneration of limestone as it is almost equally effective with lime or NaOH. Sorption of fluoride by calcium phosphates produced in situ in the reactor is the dominant mechanism of fluoride removal in the PAELD. Precipitation of CaF2 and sorption of fluoride by the limestone also contribute to the fluoride removal. High efficiency, capacity, safety, environment-friendliness, low cost and simplicity of operation make the PAELD a potential technique for rural application.

  3. Experimental oxygen isotope fractionation between siderite-water and phosphoric acid liberated CO2-siderite

    USGS Publications Warehouse

    Carothers, W.W.; Adami, L.H.; Rosenbauer, R.J.

    1988-01-01

    The equilibrium fractionation of O isotopes between synthetic siderite and water has been measured at temperatures ranging from 33?? to 197??C. The fractionation between siderite and water over this temperature range can be represented by the equation: 103 ln ?? = 3.13 ?? 106T-2 - 3.50. Comparison between the experimental and theoretical fractionations is favorable only at approximately 200??C; at lower temperatures, they generally differ by up to 2 permil. Siderite was prepared by the slow addition of ferrous chloride solutions to sodium bicarbonate solutions at the experimental temperatures. It was also used to determine the O isotope fractionation factors between phosphoric acid liberated CO2 and siderite. The fractionation factors for this pair at 25?? and 50??C are 1.01175 and 1.01075, respectively. Preliminary results of the measured C isotope fractionation between siderite and Co2 also indicate C isotopic equilibrium during precipitation of siderite. The measured distribution of 13C between siderite and CO2 coincides with the theoretical values only at about 120??C. Experimental and theoretical C fractionations differ up to 3 permil at higher and lower temperatures. ?? 1988.

  4. Preparation and structural characterization of poly-mannose synthesized by phosphoric acid catalyzation under microwave irradiation.

    PubMed

    Wang, Haisong; Cheng, Xiangrong; Shi, Yonghui; Le, Guowei

    2015-05-05

    Poly-mannose with molecular weight of 2.457 kDa was synthesized using d-mannose as substrate and phosphoric acid as catalyst under the condition of microwave irradiation for the first time. The optimum reaction conditions were microwave output power of 900 W, temperature 115°C, proton concentration 2.5 mol/L, and microwave irradiation time 5 min. The actual maximum yield was 91.46%. After purified by Sepherdex G-25 column chromatography, the structural features of poly-mannose were investigated by high-performance anion-exchange chromatography (HPAEC), high-performance gel-permeation chromatography (HPGPC), infrared (IR) spectroscopy, methylation analysis and NMR spectroscopy analysis ((1)H, (13)C, COSY, TOCSY, HMQC, and HMBC). HPAEC analysis showed that the composition of synthetic polysaccharides was d-mannose, its purity was demonstrated by HPGPC as a single symmetrical sharp peak, and additionally IR spectra demonstrated the polymerization of d-mannose. Methylation analysis and NMR spectroscopy revealed that the backbone of poly-mannose consisting of (1→3)-linked β-d-Manp, (1→3)-linked α-d-Manp, and (1→6)-linked α-d-Manp residues, and the main chain were branched at the O-2, O-3, O-4, O-6 position.

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

    SciTech Connect

    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.

  6. Improved anode catalysts for coal gas-fueled phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Kackley, N. D.; McCatty, S. A.; Kosek, J. A.

    1990-07-01

    The feasibility of adapting phosphoric acid fuel cells to operate on coal gas fuels containing significant levels of contaminants such as CO, H2S and COS was investigated. The overall goal was the development of low-cost, carbon-supported anode fuel cell catalysts that can efficiently operate with a fossil fuel-derived hydrogen gas feed contaminated with carbon monoxide and other impurities. This development would reduce the cost of gas cleanup necessary in a coal gas-fueled PAFC power plant, thereby reducing the final power cost of the electricity produced. The problem to date was that the contaminant gases typically adsorb on catalytic sites and reduce the activity for hydrogen oxidation. An advanced approach investigated was to modify these alloy catalyst systems to operate efficiently on coal gas containing higher levels of contaminants by increasing the alloy catalyst impurity tolerance and ability to extract energy from the CO present through (1) generation of additional hydrogen by promoting the CO/H2 water shift reaction or (2) direct oxidation of CO to CO2 with the same result. For operation on anode gases containing high levels of CO, a Pt-Ti-Zn and Pt-Ti-Ni anode catalyst showed better performance over a Pt baseline or G87A-17-2 catalyst. The ultimate aim was to allow PAFC-based power plants to operate on coal gas fuels containing increased contaminant concentrations, thereby decreasing the need for and cost of rigorous coal gas cleanup procedures.

  7. V-shaped crystalline structures of di-n-alkyl esters of phosphoric acid.

    PubMed

    Thünemann, Andreas F; Kurth, Dirk G; Beinhoff, Matthias; Bienert, Ralf; Schulz, Burkhard

    2006-06-20

    We prepared crystals of di-n-alkyl esters of phosphoric acid with chain lengths of n = 10, 12, 14, 16, and 18. These were characterized by single-crystal X-ray analysis and differential scanning calorimetry (DSC). It was found that the alkyl chains are in an extended all-trans conformation and aligned close to perpendicular, forming V-shaped molecules. This is in strong contrast to the typical arrangement of the alkyl chains of phospholipids where the two alkyl chains are arranged parallel in the same direction (e.g., tuning fork configuration in bilayers). Additionally, it was found that the arrangement of the V-shaped molecules of the di-n-alkyl esters in neighboring stacks of the lamellar crystals is antiparallel for short chain lengths (n = 10 and 12) and parallel for the longer (n = 14 and 16). DSC reveals that the melting of the crystals increases systematically with increasing chain lengths from 48 to 82 degrees C. The contribution of each methylene group to the melting enthalpy (70-133 kJ/mol) is independent of the chain length (3.9 kJ per mol CH2).

  8. Uranium control in phosphogypsum. [In wet-process phosphoric acid production

    SciTech Connect

    Hurst, F.J.; Arnold, W.D.

    1980-01-01

    In wet-process phosphoric acid plants, both previous and recent test results show that uranium dissolution from phosphate rock is significantly higher when the rock is acidulated under oxidizing conditions than under reducing conditions. Excess sulfate and excess fluoride further enhance the distribution of uranium to the cake. Apparently the U(IV) present in the crystal lattice of the apatite plus that formed by reduction of U(IV) by FE(II) during acidulation is trapped or carried into the crystal lattice of the calcium sulfate crystals as they form and grow. The amount of uranium that distributes to hemihydrate filter cake is up to seven times higher than the amount that distributes to the dihydrate cake. About 60% of the uranium in hemihydrate cakes can be readily leached after hydration of the cake, but the residual uranium (20 to 30%) is very difficult to remove economically. Much additional research is needed to develop methods for minimizing uranium losses to calcium filter cakes.

  9. Absorption of sulfur dioxide from simulated flue gas by polyethyleneimine-phosphoric acid solution.

    PubMed

    Bo, Wen; Li, Hongxia; Zhang, Junjie; Song, Xiangjia; Hu, Jinshan; Liu, Ce

    2016-12-01

    Clean fuel technologies have been widely developed in current society because fuel combustion can directly bring about the emission of hazardous gasses such as SO2. Flue gas desulfurization by polyethyleneimine (PEI)-phosphoric acid solution is an efficient desulfurization method. In this research, the PEI and the additive H3PO4 were used as absorption solution. SO2 was absorbed by the system and desorbed from the loaded solution. The cycle operation was also analyzed. Some technology conditions such as the concentration of PEI, the temperature, the gas flow rate, the concentration of SO2 and the pH value were experimentally researched. With the optimized process, the absorption efficiency of this system could reach 98% and the desorption efficiency was over 60%, showing good absorption/desorption capability. With this efficient approach, the present study may open a new window for developing high-performance absorbents which can make SO2 be well desorbed from the loaded solution and better reused in the flue gas desulfurization.

  10. Modulated optical properties of nonpolar gallium nitride via surface in-situ functionalization with cysteamine assisted phosphoric acid

    NASA Astrophysics Data System (ADS)

    Wilkins, Stewart J.; Paskova, Tania; Ivanisevic, Albena

    2014-03-01

    In-situ functionalization of nonpolar a-plane gallium nitride (GaN) surface was achieved by adding cysteamine to phosphoric acid, aiming to modulate its optical properties. The emission properties and oxide formation were explored through surface characterization with atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and water contact angle. Nonpolar a-plane bulk GaN sample sliced from a GaN boule and nonpolar a-plane GaN thin layer heteroepitaxially grown on r-plane sapphire were used to elucidate the effects of in-situ functionalization of identical surface orientation of GaN crystals with different defect ensembles. The addition of cysteamine to the phosphoric acid solution was found to result in: (i) increased surface roughness, (ii) no change to hydrophobicity, (iii) decreased oxygen content at high solution temperatures and increased gallium and nitrogen content versus phosphoric acid solutions at similar temperatures without cysteamine. The in-situ functionalization resulted in enhanced PL intensity from the nonpolar bulk GaN, while the PL intensity from the nonpolar heteroepitaxially grown GaN layer on sapphire was significantly reduced. The opposite PL modulation was explained by the effects of different defects present in the two samples on the nonradiative recombination.

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

    PubMed

    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.

  12. Potassium-competitive acid blockers: Advanced therapeutic option for acid-related diseases.

    PubMed

    Inatomi, Nobuhiro; Matsukawa, Jun; Sakurai, Yuuichi; Otake, Kazuyoshi

    2016-12-01

    Acid-related diseases (ARDs), such as peptic ulcers and gastroesophageal reflux disease, represent a major health-care concern. Some major milestones in our understanding of gastric acid secretion and ARD treatment reached during the last 50years include 1) discovery of histamine H2-receptors and development of H2-receptor antagonists, 2) identification of H(+),K(+)-ATPase as the parietal cell proton pump and development of proton pump inhibitors (PPIs), and 3) identification of Helicobacter pylori (H. pylori) as the major cause of peptic ulcers and development of effective eradication regimens. Although PPI treatments have been effective and successful, there are limitations to their efficacy and usage, i.e. short half-life, insufficient acid suppression, slow onset of action, and large variation in efficacy among patients due to CYP2C19 metabolism. Potassium-competitive acid blockers (P-CABs) inhibit H(+),K(+)-ATPase in a reversible and K(+)-competitive manner, and exhibit almost complete inhibition of gastric acid secretion from the first dose. Many pharmaceutical companies have tried to develop P-CABs, but most of their clinical development has been discontinued due to safety concerns or a similar efficacy to PPIs. Revaprazan was developed in Korea and was the first P-CAB approved for sale. Vonoprazan, approved in 2014 in Japan, has a completely different chemical structure and higher pKa value compared to other P-CABs, and exhibits rapid onset of action and prolonged control of intragastric acidity. Vonoprazan is an effective treatment for ARDs that is especially effective in healing reflux esophagitis and for H. pylori eradication. P-CABs, such as vonoprazan, promise to further improve the management of ARDs.

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

    PubMed

    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

  14. The effect of copper sulfate, potassium permanganate, and peracetic acid on Ichthyobodo necator in channel catfish

    USDA-ARS?s Scientific Manuscript database

    Ichthyobodo necator is a single celled biflagellate that can cause significant mortalities in fish, particularly young, tank-reared fish. Copper sulfate (CuSO4), potassium permanganate (KMnO4) and peracetic acid (PAA) were evaluated for effectiveness against Ichthybodosis in juvenile channel catfis...

  15. Conversion of pollutants to fertilisers: ion exchange synthesis of potassium sulphate from acidic mine waters.

    PubMed

    Muraviev, D

    2003-01-01

    The paper reports the results obtained by the development of ion exchange synthesis of K2SO4 from the natural acidic mine waters (AMW) of Rio Tinto area (Huelva, Spain). The process flowsheet includes several sequential stages permitting production of potassium sulphate and desalinated water along with the recovery of four metals.

  16. Bacterial flora of skin of processed broilers after multiple washing in potassium hydroxide and lauric acid

    USDA-ARS?s Scientific Manuscript database

    The number of various types of bacteria on skin of processed broilers was determined after each of five consecutive washings in mixtures of potassium hydroxide (KOH) and lauric acid (LA). Breast skin was taken from carcasses obtained from a commercial processing facility. Portions of skin were washe...

  17. Influence of washing time on residual contamination of carcasses sprayed with lauric acid-potassium hydroxide

    USDA-ARS?s Scientific Manuscript database

    A series of experiments were conducted to examine reductions in bacterial contamination of broiler carcasses washed for various times in a spray cabinet with a 2% lauric acid (LA)-1% potassium hydroxide (KOH) solution (w/v). Forty eviscerated carcasses and 5 ceca were obtained from the processing li...

  18. Role of lauric acid-potassium hydroxide concentration on bacterial contamination of spray washed broiler carcasses

    USDA-ARS?s Scientific Manuscript database

    A series of experiments were conducted to examine reductions in bacterial contamination of broiler carcasses washed in a spray cabinet with various concentrations of lauric acid (LA)-potassium hydroxide (KOH) solutions. Fifty eviscerated carcasses and 5 ceca were obtained from the processing line of...

  19. Influence of washing time on residual contamination of carcasses sprayed with lauric acid-potassium hydroxide.

    USDA-ARS?s Scientific Manuscript database

    A series of experiments were conducted to examine reductions in bacterial contamination of broiler carcasses washed for various times in a spray cabinet with a 2% lauric acid (LA)-1% potassium hydroxide (KOH) (w/v) solution. Forty eviscerated carcasses and 5 ceca were obtained from the processing l...

  20. The results of HLW processing using zirconium salt of dibutyl phosphoric acid

    SciTech Connect

    Fedorov, Yury; Zilberman, Boris; Shmidt, Olga; Saprikin, Vladimir; Ryasantsev, Valery

    2007-07-01

    Available in abstract form only. Full text of publication follows: Zirconium salt of dibutyl-phosphoric acid (ZS HDBP) dissolved in a diluent, is a promising solvent for liquid HLW processing. The investigations carried out earlier showed that ZS HDBP can recover a series of radionuclides (TPE, RE, U, Pu, Np, Sr) and some other elements (Mo, Ca, Fe) from aqueous solutions. The possibility of TPE and RE effective recovery and separation into appropriate fractions with high purification from each other was demonstrated as well. The results of extraction tests in the mixer-settlers in the course of liquid HLW treatment in hot cells, using ZS HDBP (0.4 M HDBP and 0.044 M Zr) dissolved in 30% TBP are presented. 30 liters of the feed solution containing TPE, RE, Sr and Cs with the total specific activity of 520 MBq/L and acidity of 2 M HNO{sub 3} were processed using the two-cycle flowsheet. TPE and RE recovery with subsequent stripping was realized in the first cycle, while Sr was recovered and concentrated in the second cycle. Raffinate of the latter contained almost all Cs. The degree of TPE and RE recovery was 104, and that of Sr was {approx}10. Decontamination factor of TPE and RE from Cs and Sr was 104, and that of Sr from TPE and Cs was 103. So, ZS HDBP can be used for separation of long-lived radionuclides from HLW with respect to radio-toxic category of the process products. (authors)

  1. Dietary Protein and Potassium, Diet-Dependent Net Acid Load, and Risk of Incident Kidney Stones.

    PubMed

    Ferraro, Pietro Manuel; Mandel, Ernest I; Curhan, Gary C; Gambaro, Giovanni; Taylor, Eric N

    2016-10-07

    Protein and potassium intake and the resulting diet-dependent net acid load may affect kidney stone formation. It is not known whether protein type or net acid load is associated with risk of kidney stones. We prospectively examined intakes of protein (dairy, nondairy animal, and vegetable), potassium, and animal protein-to-potassium ratio (an estimate of net acid load) and risk of incident kidney stones in the Health Professionals Follow-Up Study (n=42,919), the Nurses' Health Study I (n=60,128), and the Nurses' Health Study II (n=90,629). Multivariable models were adjusted for age, body mass index, diet, and other factors. We also analyzed cross-sectional associations with 24-hour urine (n=6129). During 3,108,264 person-years of follow-up, there were 6308 incident kidney stones. Dairy protein was associated with lower risk in the Nurses' Health Study II (hazard ratio for highest versus lowest quintile, 0.84; 95% confidence interval, 0.73 to 0.96; P value for trend <0.01). The hazard ratios for nondairy animal protein were 1.15 (95% confidence interval, 0.97 to 1.36; P value for trend =0.04) in the Health Professionals Follow-Up Study and 1.20 (95% confidence interval, 0.99 to 1.46; P value for trend =0.06) in the Nurses' Health Study I. Potassium intake was associated with lower risk in all three cohorts (hazard ratios from 0.44 [95% confidence interval, 0.36 to 0.53] to 0.67 [95% confidence interval, 0.57 to 0.78]; P values for trend <0.001). Animal protein-to-potassium ratio was associated with higher risk (P value for trend =0.004), even after adjustment for animal protein and potassium. Higher dietary potassium was associated with higher urine citrate, pH, and volume (P values for trend <0.002). Kidney stone risk may vary by protein type. Diets high in potassium or with a relative abundance of potassium compared with animal protein could represent a means of stone prevention. Copyright © 2016 by the American Society of Nephrology.

  2. Altered nucleic acid partitioning during phenol extraction or silica adsorption by guanidinium and potassium salts.

    PubMed

    Xu, Lei; Lv, Jun; Ling, Liefeng; Wang, Peng; Song, Ping; Su, Ruirui; Zhu, Guoping

    2011-12-15

    Nucleic acids were found to partition into the phenol phase during phenol extraction in the presence of guanidinium at certain concentrations under acidic conditions. The guanidinium-concentration-dependent nucleic acid partitioning patterns were analogous to those of the nucleic acid adsorption/partitioning onto silica mediated by guanidinium, which implied that phenol and silica interact with nucleic acids through similar mechanisms. A competition effect was observed in which the nucleic acids that had partitioned into the phenol phase or onto the silica solid phase could be recovered to the aqueous phases by potassium in a molecular weight-salt concentration-dependent manner (the higher molecular weight nucleic acids needed higher concentrations of potassium to be recovered, and vice versa). Methods were developed based on these findings to isolate total RNA from Escherichia coli. By controlling the concentrations of guanidinium and potassium salts used before phenol extraction or silica adsorption, we can selectively recover total RNA but not the high molecular weight genomic DNA in the aqueous phases. Genomic DNA-free total RNA obtained by our methods is suitable for RT-PCR or other purposes. The methods can also be adapted to isolate small RNAs or RNA in certain molecular weight ranges by changing the salt concentrations used.

  3. Influence of multi-step washing using Na2EDTA, oxalic acid and phosphoric acid on metal fractionation and spectroscopy characteristics from contaminated soil.

    PubMed

    Wei, Meng; Chen, Jiajun

    2016-11-01

    A multi-step soil washing test using a typical chelating agent (Na2EDTA), organic acid (oxalic acid), and inorganic weak acid (phosphoric acid) was conducted to remediate soil contaminated with heavy metals near an arsenic mining area. The aim of the test was to improve the heavy metal removal efficiency and investigate its influence on metal fractionation and the spectroscopy characteristics of contaminated soil. The results indicated that the orders of the multi-step washing were critical for the removal efficiencies of the metal fractions, bioavailability, and potential mobility due to the different dissolution levels of mineral fractions and the inter-transformation of metal fractions by XRD and FT-IR spectral analyses. The optimal soil washing options were identified as the Na2EDTA-phosphoric-oxalic acid (EPO) and phosphoric-oxalic acid-Na2EDTA (POE) sequences because of their high removal efficiencies (approximately 45 % for arsenic and 88 % for cadmium) and the minimal harmful effects that were determined by the mobility and bioavailability of the remaining heavy metals based on the metal stability (I R ) and modified redistribution index ([Formula: see text]).

  4. Novel fluorinated acids for phosphoric acid fuel cells. Annual report, April 1985-March 1986

    SciTech Connect

    DesMarteau, D.D.

    1986-05-01

    A program for the synthesis of bis ((perfluoroalkyl)sulfonyl) imides for evaluation as potential fuel-cell electrolytes was initiated. Three classes of compounds were prepared and submitted for electrochemical evaluation. These materials are all strong acids by virtue of the strong electron-withdrawing character of the perfluoroalkysulfonyl groups. Most of the materials have excellent hydrolytic and thermal stability and are very resistant to chemical and electrochemical oxidation. Synthesis of the materials was achieved in high yield from the readily available perfluoroalkyl-sulfonyl fluorides. The unusual properties of these nitrogen acids render them interesting subjects for chemical synthesis and selected reaction chemistry leading to new compounds is described.

  5. Reductimetric determination of peroxydisulphate, hydrogen peroxide, sodium perborate, nitrate and nitrite in concentrated phosphoric acid medium with iron(II).

    PubMed

    Murty, N K; Satyanarayana, V; Rao, Y F

    1977-12-01

    A direct reductimetric method for the determination of peroxydisulphate, hydrogen peroxide, sodium perborate, nitrate and nitrite in fairly concentrated phosphoric acid medium with iron(II) has been developed, with both potentiometric and visual end-point detection. Cacotheline, Methylene Blue, thionine, Azure A, Azure B, Azure C, Toluidine Blue, new Methylene Blue, ferroin, N-phenylanthranilic acid, p-ethoxychrysoidine and barium diphenylaminesulphonate are used as indicators. The method is useful in the analysis of binary mixtures of peroxydisulphate and peroxide or perborate and in the estimation of the nitrate content of fertilizers.

  6. Enhanced copper surface protection in aqueous solutions containing short-chain alkanoic acid potassium salts.

    PubMed

    Abelev, Esta; Starosvetsky, David; Ein-Eli, Yair

    2007-10-23

    The ability of dissolved potassium monocarboxylate salts to produce surface passivation and to inhibit aqueous corrosion of copper was studied. The electrochemical measurements indicate that the inhibiting efficiency of these compounds, with a general formula Cn-1H2n-1COOK or CnK (n=3...12), is dependent on the hydrocarbon chain length. The inhibiting efficiency was higher for a longer hydrocarbon chain of n-alkanoic acid. The degree of copper protection was found to increase with an increase in n-alkanoic acid potassium salt concentration; the optimum concentration of potassium dodecanoate (C12K) in sulfate solutions was found to be 0.07 M. The protective layers formed at the copper surface subsequent to exposure in various n-alkanoic acid potassium salt solutions were characterized by contact angle measurements, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared reflection spectroscopy. Pronounced copper protection was attributed to the growth of a protective film on the copper surface, containing both copper oxides and copper carboxylate compounds. It is suggested that the organic molecules enhance copper protection by covering copper oxides with a thin and dense organic layer, which prevents water molecules or aggressive anions from interacting with the copper surface.

  7. Phosphoric acid and copper (II) sulphate as a combined etchant and activator prior to the use of an anaerobic adhesive.

    PubMed

    Ireland, A J; Sherriff, M

    2001-01-01

    Previous work has shown that steel attachments can be bonded to etched human enamel using anaerobic adhesives, following treatment with a solution of 0.05M copper (II) sulphate. The objectives of this experiment were to determine whether simultaneous etching and activation could be performed with a combined solution of o-phosphoric acid and copper (II) sulphate. Stainless steel attachments were bonded to human enamel using an anaerobic adhesive. In each case the enamel was etched and activated using a solution of 37% o-phosphoric acid containing various concentrations of copper (II) sulphate. After bench curing for one hour, the specimens were shear bond tested to failure and the load at debond recorded in each case. Following determination of the optimum copper (II) sulphate concentration the experiment was repeated, but this time the acid was made into a gel using colloidal silica. The effect of rinse time after etching was also investigated with the gel. The results were analysed using mean force to debond (N) and 95% confidence intervals. Kaplan-Meier survival probabilities and log rank tests were also performed. Under the conditions of this experiment the optimum concentration of copper (II) sulphate was found to be 1M. When the acid was made into a gel the optimum rinsing time was found to be 60s. This experiment demonstrates that steel attachments can be bonded to enamel using anaerobic adhesives where the enamel has been simultaneously etched and activated. A combined o-phosphoric acid and copper (II) sulphate solution or gel can be used, but a conventional etch pattern is not produced.

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

    PubMed

    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 (Cp ) 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.

  9. Transient responses of phosphoric acid fuel cell power plant system. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Lu, Cheng-Yi

    1983-01-01

    An analytical and computerized study of the steady state and transient response of a phosphoric acid fuel cell (PAFC) system was completed. Parametric studies and sensitivity analyses of the PAFC system's operation were accomplished. Four non-linear dynamic models of the fuel cell stack, reformer, shift converters, and heat exchangers were developed based on nonhomogeneous non-linear partial differential equations, which include the material, component, energy balance, and electrochemical kinetic features. Due to a lack of experimental data for the dynamic response of the components only the steady state results were compared with data from other sources, indicating reasonably good agreement. A steady state simulation of the entire system was developed using, nonlinear ordinary differential equations. The finite difference method and trial-and-error procedures were used to obtain a solution. Using the model, a PAFC system, that was developed under NASA Grant, NCC3-17, was improved through the optimization of the heat exchanger network. Three types of cooling configurations for cell plates were evaluated to obtain the best current density and temperature distributions. The steady state solutions were used as the initial conditions in the dynamic model. The transient response of a simplified PAFC system, which included all of the major components, subjected to a load change was obtained. Due to the length of the computation time for the transient response calculations, analysis on a real-time computer was not possible. A simulation of the real-time calculations was developed on a batch type computer. The transient response characteristics are needed for the optimization of the design and control of the whole PAFC system. All of the models, procedures and simulations were programmed in Fortran and run on IBM 370 computers at Cleveland State University and the NASA Lewis Research Center.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Highly efficient heat recovery system for phosphoric acid fuel cells used for cooling telecommunication equipment

    NASA Astrophysics Data System (ADS)

    Ishizawa, Maki; Okada, Shigeru; Yamashita, Takashi

    To protect the global environment by using energy more efficiently, NTT is developing a phosphoric acid fuel cell (PAFC) energy system for telecommunication cogeneration systems. Fuel cells are used to provide electrical power to telecommunication equipment and the heat energy is used by absorption refrigerators to cool the telecommunication rooms throughout the year. We have recently developed a highly efficient system for recovering heat and water from the exhaust gases of a 200-kW (rated power) fuel cell. It is composed of a shell-and-tube type heat exchanger to recover high-temperature heat and a direct-contact cooler to recover the water efficiently and simply. The reformer and cathode exhaust gases from the fuel cell are first supplied to the heat exchanger and then to the cooler. The high-temperature (85-60°C) heat can be recovered, and the total efficiency including the heat recovered from the fuel-cell stack coolant can be improved by supplying the recovered heat to the dual-heat-input absorption refrigerator. The water needed for operating the fuel cell is also recovered from the exhaust gases. We are currently applying this heat and water recovery system to the PC25C-type fuel cell. Maximum total efficiency including electrical power efficiency is estimated to be 78% at the rated power of 200 kW: composed of 17% heat recovery for the fuel-cell stack coolant, 21% from the exhaust gas by improving the heat exchanger, and 40% from electrical conversion. Next, we plan to evaluate the usefulness of this heat recovery system for cooling telecommunication equipment.

  12. Synthesis and characterization of new biopolymeric microcapsules containing DEHPA-TOPO extractants for separation of uranium from phosphoric acid solutions.

    PubMed

    Outokesh, Mohammad; Tayyebi, Ahmad; Khanchi, Alireza; Grayeli, Fatemeh; Bagheri, Ghodrat

    2011-01-01

    A novel microcapsule adsorbent for separation of uranium from phosphoric acid solutions was developed by immobilizing the di(2-ethylhexyl) phosphoric acid-trioctyl phosphine oxide extractants in the polymeric matrix of calcium alginate. Physical characterization of the microcapsules was accomplished by scanning electron microscopy and thermogravimetric techniques. Equilibrium experiments revealed that both ion exchange and solvent extraction mechanisms were involved in the adsorption of [Formula: see text] ions, but the latter prevailed in a wider range of acid concentration. According to the results of kinetics study, at low acidity level, the rate controlling step was slow chemical reaction of [Formula: see text] ions with the microdroplets of extractant, whereas it changed to intraparticle diffusion at higher acid concentration. The study also attempted identification of the diffusion paths of the ions within the microcapsules, and the mechanism of change of mass transfer rate during the uptake process. The prepared microcapsules preserved their entire capacity after three cycles of adsorption, and their breakthrough behaviour was well fitted by a new formula derived from shrinking core model.

  13. Dietary acid load and chronic kidney disease in elderly adults: Protein and potassium intake.

    PubMed

    Ko, Byung-Joon; Chang, Yoosoo; Ryu, Seungho; Kim, Eun Mi; Lee, Mi Yeon; Hyun, Young Youl; Lee, Kyu-Beck

    2017-01-01

    Dietary net endogenous acid production (NEAP), which represents total dietary load of nonvolatile acid, may affect kidney function. Estimated NEAP (eNEAP) is calculated indirectly by the ratio of protein and potassium intake. A few studies are available assessing the association between eNEAP and chronic kidney disease (CKD), and its relation to dietary protein and potassium intake in the elderly. A total 1,369 community-dwelling elderly Koreans in the Kangbuk Samsung Cohort Study (KSCS) were evaluated using a food frequency questionnaire (FFQ) and comprehensive health examination. We evaluated the association between eNEAP and the CKD. We also examined their relation to protein and potassium intake. eNEAP was correlated with potassium intake (r = -0.410, P < 0.001), but was not correlated with protein intake (r = -0.004, P = 0.879). In a full multivariate adjustment for sociodemographic factors, dietary factors, and comorbidities, the participants with higher eNEAP quartiles (Q2, Q3, Q4) had higher odds of CKD compared to the lowest eNEAP quartile (Q1); OR (95% CI) were 1.47 (0.78-2.72), 1.66 (0.85-3.23), and 2.30 (1.16-4.60) respectively (P for trend = 0.019). The odds of CKD decreased for participants with higher potassium intake quartiles (Q2, Q3, Q4) compared to the lowest potassium intake quartile (Q1); OR (95% CI) were 0.52 (0.28-0.95), 0.50 (0.26-0.96), and 0.50 (0.21-0.99) respectively (P for trend = 0.050). Protein intake was not associated with CKD. The association between eNEAP and CKD was similar in subgroup analysis. Dietary acid load was associated with CKD. Among the nutrients related to dietary acid load, potassium intake was negatively associated with CKD, but protein intake was not associated with CKD in elderly adults.

  14. Effect of potassium salts in rats adapted to an acidogenic high-sulfur amino acid diet.

    PubMed

    Sabboh, Houda; Horcajada, Marie-Noëlle; Coxam, Véronique; Tressol, Jean-Claude; Besson, Catherine; Rémésy, Christian; Demigné, Christian

    2005-08-01

    Low-grade metabolic acidosis, consecutive to excessive catabolism of sulfur amino acids and a high dietary Na:K ratio, is a common feature of Western food habits. This metabolic alteration may exert various adverse physiological effects, especially on bone, muscle and kidneys. To assess the actual effects of various K salts, a model of the Westernised diet has been developed in rats: slight protein excess (20 % casein); cations provided as non-alkalinising salts; high Na:K ratio. This diet resulted in acidic urine (pH 5.5) together with a high rate of divalent cation excretion in urine, especially Mg. Compared with controls, K supplementation as KCl accentuated Ca excretion, whereas potassium bicarbonate or malate reduced Mg and Ca excretion and alkalinised urine pH (up to 8). In parallel, citraturia was strongly increased, together with 2-ketoglutarate excretion, by potassium bicarbonate or malate in the diet. Basal sulfate excretion, in the range of 1 mmol/d, was slightly enhanced in rats fed the potassium malate diet. The present model of low-grade metabolic acidosis indicates that potassium malate may be as effective as KHCO3 to counteract urine acidification, to limit divalent cation excretion and to ensure high citrate concentration in urine.

  15. Advanced phosphors

    DOEpatents

    Xiang, Xiao-Dong; Sun, Xiaodong; Schultz, Peter G.

    2000-01-01

    This invention relates to new phosphor materials and to combinatorial methods of synthesizing and detecting the same. In addition, methods of using phosphors to generate luminescence are also disclosed.

  16. Syntheses and biological activities of potent potassium channel openers derived from (+/-)-2-oxo-1-pyridin-3-yl-cyclohexanecarbothioic acid methylamide: new potassium channel openers.

    PubMed

    Brown, T J; Chapman, R F; Mason, J S; Palfreyman, M N; Vicker, N; Walsh, R J

    1993-05-28

    The syntheses and biological activities of (+/-)-2-(cyanomethylene)-1-pyridin-3-ylcyclohexanecarbothioic++ + acid methylamide (6) and trans-(+/-)-2-(cyanomethyl)-1-pyridin-3-ylcyclohexanecarbothioic acid methylamide (14) derived from (+/-)-2-oxo-1-pyridin-3-ylcyclohexanecarbothioic acid methylamide (4) are reported. Compounds were tested for antagonism of potassium-induced contraction of de-endothelialized rat aorta. The effects of modification of 6 and 14 on in vitro K(+)-channel opening activity are presented. These new series of potassium channel openers so derived are best exemplified by (+/-)-2-[2-(phenylsulfanyl)ethylidene]-1-pyridin-3-ylcyclohexan ecarbothioic acid methylamide (13d, RP 66266) and trans-(+/-)-2-[2-[(phenylsulfonyl)amino]ethyl]-1-pyridin-3- ylcyclohexanecarbothioic acid methylamide (25a, RP 66784), which have IC90 values of 3 and 0.3 nM, respectively. The potency of the most active compounds indicates a possible interaction at an extra binding site. The compounds described herein are potential antihypertensive and antianginal agents.

  17. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    NASA Astrophysics Data System (ADS)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili

    2014-10-01

    In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  18. Rigidly Tethered Bis-phosphoric Acids: Generation of Tunable Chiral Fluorescent Frameworks and Unexpected Selectivity for the Detection of Ferric Ions.

    PubMed

    Octa-Smolin, Frescilia; Mitra, Raja; Thiele, Maike; Daniliuc, Constantin G; Stegemann, Linda; Strassert, Cristian; Niemeyer, Jochen

    2017-07-26

    We describe the straightforward synthesis of a series of bis-phosphoric acids (R,R)-1 a-d, featuring two chiral 1,1'-binaphthyl-phosphoric acid units that are tethered by rigid, π-conjugated linkers. The nature of the linker has a profound influence on the properties of the bis-phosphoric acids, such as their self-association behavior and their interaction with metal ions. This led to the identification of one preferred bis-phosphoric acid (R,R)-1 d, which shows selective fluorescence quenching in the presence of ferric ions (Fe(3+) ). Thus, (R,R)-1 d could be applied for the detection of Fe(3+) , even in the presence of a variety of other metal ions. The chiral nature of the bis-phosphoric acid enables the interaction with Fe(3+) to be followed by CD spectroscopy, providing a complementary detection mode with the same probe. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Enantioselective Cycloaddition Reactions Catalyzed by BINOL-Derived Phosphoric Acids and N-Triflyl Phosphoramides: Recent Advances.

    PubMed

    Held, Felix E; Grau, Dominik; Tsogoeva, Svetlana B

    2015-09-03

    Over the last several years there has been a huge increase in the development and applications of new efficient organocatalysts for enantioselective pericyclic reactions, which represent one of the most powerful types of organic transformations. Among these processes are cycloaddition reactions (e.g., [3+2]; formal [3+3]; [4+2]; vinylogous [4+2] and 1,3-dipolar cycloadditions), which belong to the most utilized reactions in organic synthesis of complex nitrogen- and oxygen-containing heterocyclic molecules. This review presents the breakthrough realized in this field using chiral BINOL-derived phosphoric acids and N-triflyl phosphoramide organocatalysts.

  20. Modeling of facilitated transport of phenylalanine by emulsion liquid membranes with di(2-ethylhexyl)phosphoric acid as a carrier

    SciTech Connect

    Liu, X.; Liu, D.

    1998-12-01

    A mathematical model is developed in this paper to simulate the facilitated transport of phenylalanine (Phe) in emulsion liquid membrane (ELM) systems with di(2-ethylhexyl)phosphoric acid as a carrier. The model takes into account the mass transfer in both the external aqueous phase and the organic membrane phase interfacial reaction as well as membrane breakage during agitation. The model is tested by comparing theoretical predications with experimental results using Phe extraction by ELM processes. It is found that the model is valid for simulating the facilitated transport of Phe with ELM under various experimental conditions.

  1. Degradation of ascorbic acid and potassium sorbate by different Lactobacillus species isolated from packed green olives.

    PubMed

    Montaño, Alfredo; Sánchez, Antonio Higinio; Casado, Francisco Javier; Beato, Víctor Manuel; de Castro, Antonio

    2013-05-01

    The aim of this research was to ascertain the lactic acid bacteria responsible for the degradation of ascorbic acid and/or potassium sorbate, isolated from packed green olives where these additives had diminished. A total of 14 isolates were recovered from samples of different green olive containers. According to partial sequencing of the 16S rRNA coding gene, Lactobacillus parafarraginis, Lactobacillus rapi, Lactobacillus pentosus, Lactobacillus paracollinoides, and Pediococcus ethanolidurans were identified. With the exception of L. pentosus and L. paracollinoides, the other species had not been mentioned in table olives before this study. Only three of the 14 isolates metabolized ascorbic acid in MRS broth, and the products from ascorbic acid in modified MRS broth without carbon sources were acetic and lactic acids. Except for the two L. rapi and the two P. ethanolidurans strains, the remaining 10 isolates depleted potassium sorbate added into MRS broth to some extent. The product generated by three of these strains was confirmed to be trans-4-hexenoic acid. The degradation of ascorbate or sorbate by lactic acid bacteria should be taken into account when these additives are used in food products where this group of bacteria may be present. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Injection of air into the headspace improves fermentation of phosphoric acid pretreated sugarcane bagasse by Escherichia coli MM170.

    PubMed

    Nieves, I U; Geddes, C C; Mullinnix, M T; Hoffman, R W; Tong, Z; Castro, E; Shanmugam, K T; Ingram, L O

    2011-07-01

    Microaeration (injecting air into the headspace) improved the fermentation of hemicellulose hydrolysates obtained from the phosphoric acid pretreatment of sugarcane bagasse at 170°C for 10 min. In addition, with 10% slurries of phosphoric acid pretreated bagasse (180°C, 10 min), air injection into the headspace promoted xylose utilization and increased ethanol yields from 0.16 to 0.20 g ethanol/g bagasse dry weight using a liquefaction plus simultaneous saccharification and co-fermentation process (L+SScF). This process was scaled up to 80 L using slurries of acid pretreated bagasse (96 h incubation; 0.6L of air/min into the headspace) with ethanol yields of 312-347 L (82-92 gal) per tone (dry matter), corresponding to 0.25 and 0.27 g/g bagasse (dry weight). Injection of small amounts of air into the headspace may provide a convenient alternative to subsurface sparging that avoids problems of foaming, sparger hygiene, flotation of particulates, and phase separation.

  3. Dimensionally-stable phosphoric acid-doped polybenzimidazoles for high-temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Xiaobai; Ma, Hongwei; Shen, Yanchao; Hu, Wei; Jiang, Zhenhua; Liu, Baijun; Guiver, Michael D.

    2016-12-01

    Phosphoric acid-doped polybenzimidazole (PA-m-PBI) membranes are widely investigated for high temperature proton exchange membrane fuel cells because of their low cost and high performance. For this system, a major challenge is in achieving a good compromise between the phosphoric acid doping level and the membrane dimensional-mechanical stability. Different from the established PA-m-PBI system, the present work investigates two types of PA-PBI membranes incorporating flexible ether linkages and asymmetric bulky pendants (phenyl and methylphenyl), which exhibit much better dimensional-mechanical stability after immersing in PA solution, even at high temperature for an extended period. This superior stability allowed higher acid doping levels (20.6 and 24.6) to be achieved, thus increasing proton conductivity (165 and 217 mS cm-1 at 200 °C under anhydrous conditions) as well as significantly improving fuel cell performance. The peak power densities in hydrogen/air fuel cell were 279 and 320 mW cm-2 at 160 °C, without humidification. Molecular simulation, density and fractional free volume, and wide-angle X-ray diffraction were used to investigate their structure-property relationships.

  4. Crystallization of calcium sulfate dihydrate under simulated conditions of phosphoric acid production in the presence of aluminum and magnesium ions

    NASA Astrophysics Data System (ADS)

    Rashad, M. M.; Mahmoud, M. H. H.; Ibrahim, I. A.; Abdel-Aal, E. A.

    2004-06-01

    The effect of Al 3+ and Mg 2+ ions, as additives, on the crystallization of gypsum was studied under simulated conditions of the phosphoric acid production. Calcium hydrogen phosphate and sulfuric acid were mixed with dilute phosphoric acid at 80°C, and the turbidity of the reaction mixture was measured at different time periods to calculate the induction time of gypsum crystals formation. Addition of Al 3+ ions up to 2% decreased the induction time and increased the growth efficiency while addition of Mg 2+ increased the induction time and decreased the growth efficiency compared with in absence of additives. Interestingly, the crystals mean and median diameters were found to increase in the presence of Al 3+ and decrease in the presence of Mg 2+. The surface energy increased with Al 3+ and decreased with Mg 2+ compared to the baseline (without additives). Gypsum morphology changed from needle-like type in absence of additives to thick-rhombic in the presence of Al 3+ ions.

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

    PubMed

    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., <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 approximately 21.7 and approximately 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(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. Effect of deep-fat frying on ascorbic acid, carotenoids and potassium contents of plantain cylinders.

    PubMed

    Rojas-Gonzalez, Juan A; Avallone, Sylvie; Brat, Pierre; Trystram, Gilles; Bohuon, Philippe

    2006-01-01

    The influence of thermal treatment (frying of plantain) on the micronutrients ascorbic acid, potassium and carotenoids is evaluated. Cylinders (diameter 30 mm, thickness 10 mm) of plantain (Musa AAB 'barraganete') were fried at four thermal treatments (120-180 degrees C and from 24 to 4 min) to obtain products with approximately the same water content (approximately 0.8+/-0.02 kg/kg1) and fat content (approximately 0.15+/-0.06 kg/kg). The thermal study used the cook value and the mean cook value as indicators of the effect of several different treatment temperatures and times on quality. Deep-fat frying had no significant effect on carotenoid contents at any frying conditions, and on potassium content, except at 120 degrees C and 24 min (loss acid. The process with the greatest effect was low temperature and long time (120 degrees C/24 min), as observed for potassium and ascorbic acid. These results are in agreement with other studies that demonstrated short thermal treatments at high temperatures protect food nutritional quality, as shown by the cook value and the mean cook value. In our work, deep-fat frying of plantain preserved most of the micronutrient contents that were evaluated.

  7. Polyunsaturated fatty acids are cerebral vasodilators via the TREK-1 potassium channel.

    PubMed

    Blondeau, Nicolas; Pétrault, Olivier; Manta, Stella; Giordanengo, Valérie; Gounon, Pierre; Bordet, Régis; Lazdunski, Michel; Heurteaux, Catherine

    2007-07-20

    Vessel occlusion is the most frequent cause for impairment of local blood flow within the brain resulting in neuronal damage and is a leading cause of disability and death worldwide. Polyunsaturated fatty acids and especially alpha-linolenic acid improve brain resistance against cerebral ischemia. The purpose of the present study was to evaluate the effects of polyunsaturated fatty acids and particularly alpha-linolenic acid on the cerebral blood flow and on the tone of vessels that regulate brain perfusion. alpha-Linolenic acid injections increased cerebral blood flow and induced vasodilation of the basilar artery but not of the carotid artery. The saturated fatty acid palmitic acid did not produce vasodilation. This suggested that the target of the polyunsaturated fatty acids effect was the TREK-1 potassium channel. We demonstrate the presence of this channel in basilar but not in carotid arteries. We show that vasodilations induced by the polyunsaturated fatty acid in the basilar artery as well as the laser-Doppler flow increase are abolished in TREK-1(-/-) mice. Altogether these data indicate that TREK-1 activation elicits a robust dilation that probably accounts for the increase of cerebral blood flow induced by polyunsaturated fatty acids such as alpha-linolenic acid or docosahexanoic acid. They suggest that the selective expression and activation of TREK-1 in brain collaterals could play a significant role in the protective mechanisms of polyunsaturated fatty acids against stroke by providing residual circulation during ischemia.

  8. Effects of impurities on phase transition changes according to heat treatment of porous anodic alumina fabricated in oxalic acid and phosphoric acid electrolytes

    NASA Astrophysics Data System (ADS)

    Cho, Sam Yeon; Kim, Jin Woo; Bu, Sang Don

    2015-05-01

    In this study, porous anodic alumina (PAA) was fabricated using oxalic acid and phosphoric acid as electrolytes, and the effects of impurities on the phase transition of PAA according to changes in the heat-treatment temperature were investigated. The average pore diameter of PAA fabricated using oxalic acid and phosphoric acid increased from 43 nm to 64 nm and from 145 nm to 183 nm, respectively, in proportion to the increase in the heat-treatment temperature. An X-ray diffraction (XRD) structure analysis revealed the structure of PAA fabricated in oxalic acid to be amorphous at or below 800°C and it changed to γ-alumina at 850°C. At higher temperatures, as the heattreatment temperature was increased, a coexistence of γ- and δ-alumina phases was observed in the 900-1000°C range, and the existence of δ-alumina was observed only at 1050°C. Finally, at 1100°C, a coexistence of δ- and α-alumina phases was observed. On the other hand, for PAA fabricated in phosphoric acid, while an amorphous structure appeared at or below 800°C, as was the case with PAA fabricated in oxalic acid, only δ-alumina existed in the 850-1100°C range. On the basis of 27Al magic-angle-spinning nuclear magnetic resonance (MAS NMR) and Fourier transform infrared spectrometry (FT-IR) results, we concluded that such a discrepancy in the phase transition was attributable to interactions between impurities originating from the electrolytes.

  9. Measurements of the effects of thermal contact resistance on steady state heat transfer in phosphoric-acid fuel cell stack

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Alkasab, Kalil A.

    1991-01-01

    The influence of the thermal contact resistance on the heat transfer between the electrode plates, and the cooling system plate in a phosphoric-acid fuel-cell stack was experimentally investigated. The investigation was conducted using a set-up that simulates the operating conditions prevailing in a phosphoric acid fuel-cell stack. The fuel-cell cooling system utilized three types of coolants, water, engine oil, and air, to remove excess heat generated in the cell electrode and to maintain a reasonably uniform temperature distribution in the electrode plate. The thermal contact resistance was measured as a function of pressure at the interface between the electrode plate and the cooling system plate. The interface pressure range was from 0 kPa to 3448 kPa, while the Reynolds number for the cooling limits varied from 15 to 79 for oil, 1165 to 6165 for water, and 700 to 6864 for air. Results showed that increasing the interface pressure resulted in a higher heat transfer coefficient.

  10. Optimization of preparation of activated carbon from cotton stalk by microwave assisted phosphoric acid-chemical activation.

    PubMed

    Deng, Hui; Zhang, Genlin; Xu, Xiaolin; Tao, Guanghui; Dai, Jiulei

    2010-10-15

    The preparation of activated carbon (AC) from cotton stalk was investigated in this paper. Orthogonal array experimental design method was used to optimize the preparation of AC using microwave assisted phosphoric acid. Optimized parameters were radiation power of 400 W, radiation time of 8 min, concentration of phosphoric acid of 50% by volume and impregnation time of 20 h, respectively. The surface characteristics of the AC prepared under optimized condition were examined by pore structure analysis, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Pore structure analysis shows that mecropores constitute more of the porosity of the prepared AC. Compared to cotton stalk, different functionalities and morphology on the carbon surfaces were formed in the prepared process. The adsorption capacity of the AC was also investigated by removing methylene blue (MB) in aqueous solution. The equilibrium data of the adsorption was well fitted to the Langmuir isotherm. The maximum adsorption capacity of MB on the prepared AC is 245.70 mg/g. The adsorption process follows the pseudo-second-order kinetic model.

  11. Studies of the Mechanism and Origins of Enantioselectivity for the Chiral Phosphoric Acid-Catalyzed Stereoselective Spiroketalization Reactions.

    PubMed

    Khomutnyk, Yaroslav Ya; Argüelles, Alonso J; Winschel, Grace A; Sun, Zhankui; Zimmerman, Paul M; Nagorny, Pavel

    2016-01-13

    Mechanistic and computational studies were conducted to elucidate the mechanism and the origins of enantiocontrol for asymmetric chiral phosphoric acid-catalyzed spiroketalization reactions. These studies were designed to differentiate between the S(N)1-like, S(N)2-like, and covalent phosphate intermediate-based mechanisms. The chiral phosphoric acid-catalyzed spiroketalization of deuterium-labeled cyclic enol ethers revealed a highly diastereoselective syn-selective protonation/nucleophile addition, thus ruling out long-lived oxocarbenium intermediates. Hammett analysis of the reaction kinetics revealed positive charge accumulation in the transition state (ρ = -2.9). A new computational reaction exploration method along with dynamics simulations supported an asynchronous concerted mechanism with a relatively short-lived polar transition state (average lifetime = 519 ± 240 fs), which is consistent with the observed inverse secondary kinetic isotope effect of 0.85. On the basis of these studies, a transition state model explaining the observed stereochemical outcome has been proposed. This model predicts the enantioselective formation of the observed enantiomer of the product with 92% ee, which matches the experimentally observed value.

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

    SciTech Connect

    Lassinantti Gualtieri, Magdalena

    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.

  13. Improved detection of multi-phosphorylated peptides in the presence of phosphoric acid in liquid chromatography/mass spectrometry

    SciTech Connect

    Kim, Jeongkwon; Camp, David G.; Smith, Richard D.

    2004-02-18

    In contrast to lower phosphorylation states (e.g., the tryptic monophosphopeptide FQpSEEQQQTEDELQDK from bovine -casein), the specific detection of multi-phosphorylated peptides (e.g. the tetraphosphopeptide RELEELNVPGEIVEpSLpSpSpSEESITR from tryptic digestion of bovine -casein) has often been problematic for liquid chromatography-mass spectrometry analysis due to their high affinity for adsorption to exposed surfaces. We observed an enhancement in the overall detection of phosphopeptides upon addition of phosphoric acid (0.1% to 1.0%) to the sample solution; a 10-fold increase in sensitivity was measured for the detection of two tryptic phosphopeptides as well as a significant improvement in the detection of the tetraphosphopeptide. Using capillary LC with an ion trap tandem mass spectrometer for detection and identification, the achievable detection limits were 50 fmol and 50 pmol for the monophosphopeptide and the tetraphosphopeptide, respectively. Phosphoric acid is believed to act as a blocking agent to available silanol groups on both the silica capillary surface and the C-18-bonded silica surface.

  14. Measurements of the effects of thermal contact resistance on steady state heat transfer in phosphoric-acid fuel cell stack

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Alkasab, Kalil A.

    1991-01-01

    The influence of the thermal contact resistance on the heat transfer between the electrode plates, and the cooling system plate in a phosphoric-acid fuel-cell stack was experimentally investigated. The investigation was conducted using a set-up that simulates the operating conditions prevailing in a phosphoric acid fuel-cell stack. The fuel-cell cooling system utilized three types of coolants, water, engine oil, and air, to remove excess heat generated in the cell electrode and to maintain a reasonably uniform temperature distribution in the electrode plate. The thermal contact resistance was measured as a function of pressure at the interface between the electrode plate and the cooling system plate. The interface pressure range was from 0 kPa to 3448 kPa, while the Reynolds number for the cooling limits varied from 15 to 79 for oil, 1165 to 6165 for water, and 700 to 6864 for air. Results showed that increasing the interface pressure resulted in a higher heat transfer coefficient.

  15. Modulation of the mitochondrial large-conductance calcium-regulated potassium channel by polyunsaturated fatty acids.

    PubMed

    Olszewska, Anna; Bednarczyk, Piotr; Siemen, Detlef; Szewczyk, Adam

    2014-10-01

    Polyunsaturated fatty acids (PUFAs) and their metabolites can modulate several biochemical processes in the cell and thus prevent various diseases. PUFAs have a number of cellular targets, including membrane proteins. They can interact with plasma membrane and intracellular potassium channels. The goal of this work was to verify the interaction between PUFAs and the most common and intensively studied mitochondrial large conductance Ca(2+)-regulated potassium channel (mitoBKCa). For this purpose human astrocytoma U87 MG cell lines were investigated using a patch-clamp technique. We analyzed the effects of arachidonic acid (AA); eicosatetraynoic acid (ETYA), which is a non-metabolizable analog of AA; docosahexaenoic acid (DHA); and eicosapentaenoic acid (EPA). The open probability (Po) of the channel did not change significantly after application of 10μM ETYA. Po increased, however, after adding 10μM AA. The application of 30μM DHA or 10μM EPA also increased the Po of the channel. Additionally, the number of open channels in the patch increased in the presence of 30μM EPA. Collectively, our results indicate that PUFAs regulate the BKCa channel from the inner mitochondrial membrane. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Usnic Acid Potassium Salt: An Alternative for the Control of Biomphalaria glabrata (Say, 1818)

    PubMed Central

    Lima, Vera L. M.; Pereira, Eugênia C.; Falcão, Emerson P. S.; Melo, Ana M. M. A.; da Silva, Nicácio Henrique

    2014-01-01

    In Brazil, the snail Biomphalaria glabrata is the most important vector of schistosomiasis due to its wide geographical distribution, high infection rate and efficient disease transmission. Among the methods of schistosomiasis control, the World Health Organization recommends the use of synthetic molluscicides, such as niclosamide. However, different substances of natural origin have been tested as alternatives for the control or eradication of mollusks. The literature describes the antitumor, antimicrobial and antiviral properties of usnic acid as well as other important activities of common interest between medicine and the environment. However, usnic acid has a low degree of water solubility, which can be a limiting factor for its use, especially in aquatic environments, since the organic solvents commonly used to solubilize this substance can have toxic effects on aquatic biota. Thus, the aim of the present study was to test the potassium salt of usnic acid (potassium usnate) with regard to molluscicidal activity and toxicity to brine shrimp (Artemia salina). To obtain potassium usnate, usnic acid was extracted with diethyl ether isolated and purified from the lichen Cladonia substellata. Biological assays were performed with embryos and adult snails of B. glabrata exposed for 24 h to the usnate solution solubilized in dechlorinated water at 2.5; 5 and 10 µg/ml for embryos, 0.5; 0.9; 1;5 and 10 µg/ml for mollusks and 0.5; 1; 5; 10 µg/ml for A. salina. The lowest lethal concentration for the embryos and adult snails was 10 and 1 µg/ml, respectively. No toxicity to A. salina was found. The results show that modified usnic acid has increased solubility (100%) without losing its biological activity and may be a viable alternative for the control of B. glabrata. PMID:25375098

  17. Enantioselective Synthesis of α-Mercapto-β-amino Esters via Rh(II)/Chiral Phosphoric Acid-Cocatalyzed Three-Component Reaction of Diazo Compounds, Thiols, and Imines.

    PubMed

    Xiao, Guolan; Ma, Chaoqun; Xing, Dong; Hu, Wenhao

    2016-12-02

    An enantioselective method for the synthesis of α-mercapto-β-amino esters has been developed via a rhodium(II)/chiral phosphoric acid-cocatalyzed three-component reaction of diazo compounds, thiols, and imines. This transformation is proposed to proceed through enantioselective trapping of the sulfonium ylide intermediate generated in situ from the diazo compound and thiol by the phosphoric acid-activated imine. With this method, a series of α-mercapto-β-amino esters were obtained in good yields with moderate to good stereoselectivities.

  18. Thermoluminescent phosphor

    DOEpatents

    Lasky, Jerome B.; Moran, Paul R.

    1978-01-01

    A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta rays in the presence of a background of more penetrating radiation.

  19. The effect of phosphoric acid pre-etching and thermocycling on self-etching adhesive enamel bonding.

    PubMed

    Sheets, James L; Wilcox, Charles W; Barkmeier, Wayne W; Nunn, Martha E

    2012-02-01

    When inserting a resin-bonded prosthesis, it is not known whether pumicing, rinsing, and using a self-etching primer (SE) on prepared surfaces is sufficient or whether the use of an additional conventional acid etchant is warranted due to the increased time and risk of contamination. The purpose of this study was to evaluate the effects of pre-etching with phosphoric acid (PA) and thermocycling (TC) on the enamel shear bond strength (SBS) of an autopolymerizing adhesive system on ground enamel. Human teeth were embedded in phenolic rings with methyl methacrylate resin, and their enamel surfaces were ground flat to a 600 grit surface. The teeth were then divided into 4 subsets (n=22): 1) PSN, PA pre-etch with SE, no TC; 2) PST, PA pre-etch with self-etching primer and TC; 3) SEN, self-etching primer alone, no TC; and 4) SET, self-etching primer and TC. A multifactorial study design was used to evaluate 2 factors (pre-etching with PA and TC) at 2 levels (presence or absence) by grouping different subsets. Pre-etch consisted of teeth being etched for 30 seconds with PA, rinsed, re-etched, and rinsed. Self-etching consisted of 60 seconds with ED Primer. Rods of Rexillium III, airborne-particle abraded with 50 μm aluminum oxide, were bonded to enamel surfaces with Panavia 21 OP under a 19.6 N load. Thermocycling consisted of alternating between water baths of 5 ± 2°C and 55 ± 2°C for 5000 cycles. Shear bond strength (SBS) was determined by loading the specimens to failure at a crosshead speed of 1 mm/min. Mean values were analyzed with a 2-way ANOVA (factors were surface treatment and TC) at α=.05. Pre-etching with phosphoric acid showed greater SBS to enamel (P=.028) than the self-etching primer alone. Thermocycling did not have a significant effect (P=.424). There was a significant difference in SBS between pre-etching enamel surfaces with phosphoric acid in addition to the self-etching primer and using the self-etching primer exclusively. Thermocycling did not

  20. Evaluation of the effect of surface preparation using phosphoric acid and luting cement on the flexural strength of porcelain laminate veneering material

    PubMed Central

    Guruprasada; Rivankar, N.; Dhiman, R.K.; Viswambaran, M.

    2015-01-01

    Background Conventionally HF acid has been used for etching ceramic veneer restorations before their cementation. Studies are lacking regarding the effectiveness of phosphoric acid as a substitute for HF acid for etching the ceramic veneers. The purpose of this study was to evaluate the effectiveness of surface preparation of porcelain laminate veneers using phosphoric acid, as compared to HF acid etching in providing the necessary surface roughness conducive to development of an effective bond between the ceramic laminate and the resin luting cement. Methods 210 porcelain discs of 15 mm diameter and 0.9 mm thickness were prepared. These study samples were divided into seven groups of thirty samples each. Surfaces of the first (control) and the second group of samples were not prepared. The surfaces of other five groups were prepared with different surface treatments. Further all the groups of specimens were coated with a layer of resin luting cement. Flexural strength of each specimen was determined using universal testing machine and the results were compared. Results The combination surface treatment using alumina surface abrasion followed by etching with phosphoric acid provided the highest flexural strength with the mean flexural strength of 101.11 MPa, followed by alumina surface abrasion (95.41 MPa), and phosphoric acid surface etching (81.68 MPa). Conclusion Laminate veneers surface treated using 50 μm alumina abrasion followed by etching with phosphoric acid showed the highest flexural strengths after resin coating compared to other groups. PMID:26843743

  1. In vivo Expression of a Light-activatable Potassium Channel Using Unnatural Amino Acids

    PubMed Central

    Kang, Ji-Yong; Kawaguchi, Daichi; Coin, Irene; Xiang, Zheng; O’Leary, Dennis D. M.; Slesinger, Paul A.; Wang, Lei

    2013-01-01

    SUMMARY Optical control of protein function provides excellent spatial-temporal resolution for studying proteins in situ. Although light-sensitive exogenous proteins and ligands have been employed to manipulate neuronal activity, a method for optical control of neuronal proteins using unnatural amino acids (Uaa) in vivo is lacking. Here, we describe the genetic incorporation of a photoreactive Uaa into the pore of an inwardly-rectifying potassium channel Kir2.1. The Uaa occluded the pore, rendering the channel non-conducting, and upon brief light illumination, was released to permit outward K+ current. Expression of this photo-inducible inwardly rectifying potassium (PIRK) channel in rat hippocampal neurons created a light-activatable PIRK switch for suppressing neuronal firing. We also expressed PIRK channels in embryonic mouse neocortex in vivo and demonstrated a light-activated PIRK current in cortical neurons. The principles applied here to a potassium channel could be generally expanded to other proteins expressed in the brain to enable optical regulation. PMID:24139041

  2. Inactivation of human norovirus surrogates by benzalkonium chloride, potassium peroxymonosulfate, tannic acid, and gallic acid.

    PubMed

    Su, Xiaowei; D'Souza, Doris H

    2012-09-01

    Novel methods to effectively disinfect contact surfaces and prevent human norovirus transmission are essential. The effect of benzalkonium chloride (BAC), potassium peroxymonosulfate (KPMS), tannic acid (TA), and gallic acid (GA) on enteric virus surrogates, murine norovirus (MNV-1), feline calicivirus (FCV-F9), and bacteriophage MS2 was studied. Viruses at high (∼7 log₁₀ PFU/mL) or low (∼5 log₁₀ PFU/mL) titers were mixed with equal volumes of BAC (0.2, 0.5, and 1 mg/mL), KPMS (5, 10, and 20 mg/mL), TA (0.02 and 0.2 mg/mL), GA (0.2, 0.4, and 0.8 mg/mL), or water and incubated for 2 h at room temperature. Viral infectivity after triplicate treatments was evaluated using plaque assays in duplicate. Low titers of FCV-F9 and MNV-1 were completely reduced, while low-titer MS2 was reduced by 1.7-1.8 log₁₀ PFU/mL with BAC at all three concentrations. High-titer FCV-F9 was reduced by 2.87, 3.08, and 3.25 log₁₀ PFU/mL, and high-titer MNV-1 was reduced by 1.55, 2.32, and 2.75 log₁₀ PFU/mL with BAC at 0.1, 0.25, and 0.5 mg/mL, respectively. High-titer MS2 was reduced by ∼2 log₁₀ PFU/mL with BAC at all three concentrations. KPMS at all three concentrations reduced high and low titers of FCV-F9 and MS2 and low-titer MNV-1 to undetectable levels, while high-titer MNV-1 was reduced by 0.92 and 3.44 log₁₀ PFU/mL with KMPS at 2.5 and 5 mg/mL, respectively. TA at 0.2 mg/mL only reduced high-titer FCV-F9 by 0.98 log₁₀ PFU/mL and low-titer FCV-F9 by 1.95 log₁₀ PFU/mL. GA at 0.1, 0.2, and 0.4 mg/mL reduced low-titer FCV-F9 by 2.50, 2.36, and 0.86 log₁₀ PFU/mL, respectively with negligible effects against high-titer FCV-F9. BAC and KPMS show promise to be used as broad-spectrum contact surface disinfectants for prevention of noroviral surrogate contamination.

  3. Self-Controlled Synthesis of Hyperbranched Poly(etherketone)s from A2 + B3 Approach in Poly(phosphoric acid)

    DTIC Science & Technology

    2009-01-01

    polymerization condition was indeed strong enough to effi- ciently facilitate polycondensation via ‘‘direct’’ Friedel - Crafts reaction without gelation...Keywords: Friedel - Crafts acylation; high performance polymer; hyperbranched polymer; poly(ether-ketone)s; poly(phosphoric acid) INTRODUCTION Dendritic...Hence, the applied polymerization condition was indeed strong enough to efficiently facilitate polycondensation via ??direct?? Friedel - Crafts reaction

  4. 3D fabrication and characterization of phosphoric acid scaffold with a HA/β-TCP weight ratio of 60:40 for bone tissue engineering applications.

    PubMed

    Wang, Yanen; Wang, Kai; Li, Xinpei; Wei, Qinghua; Chai, Weihong; Wang, Shuzhi; Che, Yu; Lu, Tingli; Zhang, Bo

    2017-01-01

    A key requirement for three-dimensional printing (3-DP) at room temperature of medical implants depends on the availability of printable and biocompatible binder-powder systems. Different concentration polyvinyl alcohol (PVA) and phosphoric acid solutions were chosen as the binders to make the artificial stent biocompatible with sufficient compressive strength. In order to achieve an optimum balance between the bioceramic powder and binder solution, the biocompatibility and mechanical properties of these artificial stent samples were tested using two kinds of binder solutions. This study demonstrated the printable binder formulation at room temperature for the 3D artificial bone scaffolds. 0.6 wt% PVA solution was ejected easily via inkjet printing, with a supplementation of 0.25 wt% Tween 80 to reduce the surface tension of the polyvinyl alcohol solution. Compared with the polyvinyl alcohol scaffolds, the phosphoric acid scaffolds had better mechanical properties. Though both scaffolds supported the cell proliferation, the absorbance of the polyvinyl alcohol scaffolds was higher than that of the phosphoric acid scaffolds. The artificial stents with a hydroxyapatite/beta-tricalcium phosphate (HA/β-TCP) weight ratios of 60:40 depicted good biocompatibility for both scaffolds. Considering the scaffolds' mechanical and biocompatible properties, the phosphoric acid scaffolds with a HA/β-TCP weight ratio of 60:40 may be the best combination for bone tissue engineering applications.

  5. 3D fabrication and characterization of phosphoric acid scaffold with a HA/β-TCP weight ratio of 60:40 for bone tissue engineering applications

    PubMed Central

    Wang, Yanen; Wang, Kai; Li, Xinpei; Wei, Qinghua; Chai, Weihong; Wang, Shuzhi; Che, Yu; Lu, Tingli; Zhang, Bo

    2017-01-01

    A key requirement for three-dimensional printing (3-DP) at room temperature of medical implants depends on the availability of printable and biocompatible binder-powder systems. Different concentration polyvinyl alcohol (PVA) and phosphoric acid solutions were chosen as the binders to make the artificial stent biocompatible with sufficient compressive strength. In order to achieve an optimum balance between the bioceramic powder and binder solution, the biocompatibility and mechanical properties of these artificial stent samples were tested using two kinds of binder solutions. This study demonstrated the printable binder formulation at room temperature for the 3D artificial bone scaffolds. 0.6 wt% PVA solution was ejected easily via inkjet printing, with a supplementation of 0.25 wt% Tween 80 to reduce the surface tension of the polyvinyl alcohol solution. Compared with the polyvinyl alcohol scaffolds, the phosphoric acid scaffolds had better mechanical properties. Though both scaffolds supported the cell proliferation, the absorbance of the polyvinyl alcohol scaffolds was higher than that of the phosphoric acid scaffolds. The artificial stents with a hydroxyapatite/beta-tricalcium phosphate (HA/β-TCP) weight ratios of 60:40 depicted good biocompatibility for both scaffolds. Considering the scaffolds’ mechanical and biocompatible properties, the phosphoric acid scaffolds with a HA/β-TCP weight ratio of 60:40 may be the best combination for bone tissue engineering applications. PMID:28406922

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

    Treesearch

    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...

  7. δ18O anchoring to VPDB: calcite digestion with 18O-adjusted ortho-phosphoric acid.

    PubMed

    Wendeberg, Magnus; Richter, Jürgen M; Rothe, Michael; Brand, Willi A

    2011-04-15

    For anchoring CO(2) isotopic measurements on the δ(18)O(VPD-CO2) scale, the primary reference material (NBS 19 calcite) needs to be digested using concentrated ortho-phosphoric acid. During this procedure, great care must be taken to ensure that the isotopic composition of the liberated gas is accurate. Apart from controlling the reaction temperature to ±0.1 °C, the potential for oxygen isotope exchange between the produced CO(2) and water must be kept to a minimum. The water is usually assumed to reside on the walls in the headspace of the reaction vessel. We demonstrate here that a large fraction of the exchange may also occur with water inside the acid. Our results indicate that both exchange reactions have a significant impact on the results and may have largely been responsible for scale inconsistencies between laboratories in the past. The extent of CO(2)/H(2)O oxygen exchange depends on the concentration (amount of free water) in the acid. For acids with a nominal H(3)PO(4) mass fraction of less than 102%, oxygen isotope exchange can create a substantial isotopic bias during high-precision measurements with the degree of the alteration being proportional to the effective isotopic contrast between the acid and the CO(2) released from the calcite. Water evaporating from the acid at 25 °C has a δ(18)O value of -34.5‰ relative to the isotopic composition of the whole acid. This large fractionation is likely to occur in two steps; by exchange with phosphate, water inside the acid is decreased in oxygen-18 relative to the bulk acid by ∼ -22‰. This water is then fractionated further during evaporation. Oxygen exchange with both water inside the acid and water condensate in the headspace can contribute to the measured isotopic signature depending on the experimental parameters. The system employed for this study has been specifically designed to minimize oxygen exchange with water. However, the amount of altered CO(2) for a 95% H(3)PO(4) at 25 °C still

  8. Nitric-phosphoric acid etching effects on the surface chemical composition of CdTe thin film.

    NASA Astrophysics Data System (ADS)

    Irfan, Irfan; Ding, Huanjun; Xia, Wei; Lin, Hao; Tang, Ching W.; Gao, Yongli

    2009-03-01

    Nitric-phosphoric (NP) acid etching has been regarded as one of the most successful methods for the formation of low resistance back contact with the metal electrode in CdTe based solar cells. We report back surface chemical composition for eight different durations of NP etching of CdTe polycrystalline thin film. We studied the surfaces with x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IEPS) and atomic force microscopy (AFM). Etching dependence on the back surface composition and electronic structure was observed. Valence and conduction band shifts relative to the Fermi level of the system with different etching duration were analyzed. The sample was left in open ambient condition for three weeks and XPS data were obtained again in order to study the difference in surface chemical composition with the pristine CdTe film. Unetched and highly etched part of the sample were sputtered and the depth profile analyzed.

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

    PubMed

    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.

  10. Passive state behavior of special austenitic and ferritic stainless steels in phosphoric acid polluted by sulfide ions

    SciTech Connect

    El Hajjaji, S.; Aries, L.; Pebere, N.; Dabosi, F.; Audouard, J.P.; Bachir, A.B.

    1996-11-01

    The passive state behavior of the ferritic Z1 CD 29-4 stainless steel in industrial phosphoric acid (40 wt% H{sub 3}PO{sub 4} with 1,000 ppm chloride and 330 ppm sulfate) polluted with 20 ppm sulfide ions was compared to that of the austenitic Z2 CNDU 25-25 SS, which is known for its high corrosion resistance. Comparison was made using electrochemical techniques, electron spectroscopy for chemical analysis, and secondary ion mass spectroscopy. The presence of sulfide ions increased the dissolution rate of the austenitic SS to near that of the ferritic SS. Degradation of the protective passive film on the austenitic SS was attributed to formation of compounds of nickel and copper at the expense of chromium and molybdenum. Behavior of the two SS in the passive state was not very different.

  11. Luminescence properties of compounds of europium(III) with quinaldic acid and phosphor-containing neutral ligands

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.

    2016-06-01

    Luminescent complex mixed-ligand compounds of europium(III) with quinaldic acid and phosphor- containing neutral ligands have been obtained. Their composition and structure have been determined. The thermal and spectral-luminescent properties of the obtained complex mixed-ligand compounds of europium( III) have been studied. It is shown that, during thermolysis, a water molecule and neutral ligand are detached in two stages with endothermic effects. It is established that quinaldinate ion is coordinated to europium(III) ion in a bidentate fashion. The Stark structure of the 5 D 0-7 F j ( j = 0, 1, 2) transitions in low-temperature luminescence spectra of complex compounds of europium(III) has been analyzed.

  12. Kinetics and thermodynamics of basic dye sorption on phosphoric acid esterifying soybean hull with solid phase preparation technique.

    PubMed

    Gong, Renmin; Sun, Jin; Zhang, Demin; Zhong, Keding; Zhu, Guoping

    2008-07-01

    In this paper, the solid phase preparation method of a cationic sorbent, which bears hydroxyl groups of phosphoric acid derived from esterified soybean hull (ESH), was reported. The sorption kinetics and thermodynamics of two basic dyes, acridine orange (AO) and malachite green (MG), from aqueous solution onto ESH were investigated with a batch system. The isothermal data of dye sorptions followed the Langmuir model better than the Freundlich model. The maximum sorption capacity (Q(m)) of ESH for AO and MG was 238.1 mg/g and 178.57 mg/g, respectively. The dye sorption processes could be described by the pseudo-second-order kinetic model. The thermodynamic study indicated that the dye sorptions were spontaneous and exothermic. Lower temperatures were favorable for the sorption processes.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Determination of Activity Coefficients of di-(2-ethylhexyl) Phosphoric Acid Dimer in Select Organic Solvents Using Vapor Phase Osmometry

    SciTech Connect

    Michael F. Gray; Peter Zalupski; Mikael Nilsson

    2013-08-01

    Effective models for solvent extraction require accurate characterization of the nonideality effects for each component, including the extractants. In this study, the nonideal behavior of the industrial extractant di(2-ethylhexyl) phosphoric acid has been investigated using vapor pressure osmometry (VPO). From the osmometry data, activity coefficients for the HDEHP dimer were obtained based on a formulation of the regular solution theory of Scatchard and Hildebrand, and the Margules two- and three-suffix equations. The results show similarity with a slope-analysis based relation from previous literature, although important differences are highlighted. The work points towards VPO as a useful technique for this type of study, but care must be taken with the choice of standard and method of analysis.

  15. Laser Fired Local Back Contact C-Si Solar Cells Using Phosphoric Acid for Back Surface Field

    NASA Astrophysics Data System (ADS)

    Balaji, Nagarajan; Park, Cheolmin; Ju, Minkyu; Lee, Seunghwan; Kim, Jungmo; Chung, Sungyoun; Raja, Jayapal; Yi, Junsin

    2015-04-01

    We report on a laser doping process for the formation of a local back surface field (BSF) using phosphoric acid (H3PO4) for n-type passivated emitter rear totally diffused silicon solar cells. The sheet resistance of the BSF layer was varied by changing the H3PO4 concentration. The BSF layer was passivated using SiN x . With the passivated BSF, the LBC solar cell shows an improved open circuit voltage. A laser power of 44 mW with 10 kHz resulted in a 45-Ω/sq BSF layer with effective lifetime of 290 μs and a higher V oc of 623 mV. With the optimized laser parameters, devices with the best electrical results yielded a short circuit current density of 36 mA/cm2 and an efficiency of 18.26%.

  16. Morphology of the diastereomeric salt of the alkaloid ephedrine and a chlorine substituted cyclic phosphoric acid (CLINAM)

    NASA Astrophysics Data System (ADS)

    Strom, C. S.; Leusen, F. J. J.; Geertman, R. M.; Ariaans, G. J. A.

    1997-01-01

    The morphology of the diastereomeric salt of the alkaloid ephedrine and a chlorine substituted cyclic phosphoric acid is studied theoretically by means of a first-principles application of Hartman's PBC theory. A rigorous graph-theoretic derivation of the F slices of CLINAM and 2,4-DICLINAM has yielded all possible growth layers and their orientations. The Coulomb and Van der Waals contributions to the energy quantities characterizing CLINAM are calculated, using the Ewald formulation adjusted to lamina shapes, exactly and free from adjustable parameters. Several schemes of computing partial charges, in combination with energy minimization techniques are used for computing the atomic point charges. The structural morphology follows from the total attachment energies. The theoretical growth habit depends sensitively on the choice of the employed atomic charge scheme. The theoretical morphology of CLINAM crystals is discussed in the light of experimental results.

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

    NASA Astrophysics Data System (ADS)

    Wen, Wen; Li, Haibin; Chen, Xiaojing; Chang, Chengkang

    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.

  18. In the Bottlebrush Garden: The Structural Aspects of Coordination Polymer Phases formed in Lanthanide Extraction with Alkyl Phosphoric Acids.

    PubMed

    Ellis, Ross J; Demars, Thomas; Liu, Guokui; Niklas, Jens; Poluektov, Oleg G; Shkrob, Ilya A

    2015-09-03

    Coordination polymers (CPs) of metal ions are central to a large variety of applications, such as catalysis and separations. These polymers frequently occur as amorphous solids that segregate from solution. The structural aspects of this segregation remain elusive due to the dearth of the spectroscopic techniques and computational approaches suitable for probing such systems. Therefore, there is a lacking of understanding of how the molecular building blocks give rise to the mesoscale architectures that characterize CP materials. In this study we revisit a CP phase formed in the extraction of trivalent lanthanide ions by diesters of the phosphoric acid, such as the bis(2-ethylhexyl)phosphoric acid (HDEHP). This is a well-known system with practical importance in strategic metals refining and nuclear fuel reprocessing. A CP phase, referred to as a "third phase", has been known to form in these systems for half a century, yet the structure of the amorphous solid is still a point of contention, illustrating the difficulties faced in characterizing such materials. In this study, we follow a deductive approach to solving the molecular structure of amorphous CP phases, using semiempirical calculations to set up an array of physically plausible models and then deploying a suite of experimental techniques, including optical, magnetic resonance, and X-ray spectroscopies, to consecutively eliminate all but one model. We demonstrate that the "third phase" consists of hexagonally packed linear chains in which the lanthanide ions are connected by three O-P-O bridges, with the modifying groups protruding outward, as in a bottlebrush. The tendency to yield linear polynuclear oligomers that is apparent in this system may also be present in other systems yielding the "third phase", demonstrating how molecular geometry directs polymeric assembly in hybrid materials. We show that the packing of bridging molecules is central to directing the structure of CP phases and that by

  19. Nanostructure evaluation of healthy and fluorotic dentin by atomic force microscopy before and after phosphoric acid etching.

    PubMed

    Zavala-Alonso, Veronica; Aguilera-Flores, Rafael; Patiño-Marin, Nuria; Martinez-Castañon, Gabriel A; Anusavice, Kenneth J; Loyola-Rodriguez, Juan Pablo

    2011-01-01

    The aim was to characterize by atomic force microscopy (AFM) the nanostructure of human dentin surfaces affected by dental fluorosis (DF) before and after phosphoric acid etching. This study included 240 human dentin samples classified according to the severity of DF, which were divided into four groups using the Thylstrup-Fejerskov Index (TFI). Samples were analyzed by AFM before and after acid etching for 15, 30, and 60 s. The roughness (R(a)) for healthy dentin, and dentin with mild, moderate, and severe fluorosis were 440 nm, 442 nm, 445 nm, and 449 nm, respectively. After 15, 30, and 60 s of acid etching, all healthy and fluorotic dentin samples increased in roughness (p<0.05). The diameter of dentinal tubule orifices (D(t)) in healthy human dentin increased after acid etching for 60 s. We conclude that effective etching times are 15 s for healthy and mild dentin fluorosis, 30-s for moderately fluorosed dentin, and 45-60 s for severe fluorotic dentin.

  20. Protonated Form: The Potent Form of Potassium-Competitive Acid Blockers

    PubMed Central

    Luo, Hua-Jun; Deng, Wei-Qiao; Zou, Kun

    2014-01-01

    Potassium-competitive acid blockers (P-CABs) are highly safe and active drugs targeting H+,K+-ATPase to cure acid-related gastric diseases. In this study, we for the first time investigate the interaction mechanism between the protonated form of P-CABs and human H+,K+-ATPase using homology modeling, molecular docking, molecular dynamics and binding free energy calculation methods. The results explain why P-CABs have higher activities with higher pKa values or at lower pH. With positive charge, the protonated forms of P-CABs have more competitive advantage to block potassium ion into luminal channel and to bind with H+,K+-ATPase via electrostatic interactions. The binding affinity of the protonated form is more favorable than that of the neutral P-CABs. In particular, Asp139 should be a very important binding site for the protonated form of P-CABs through hydrogen bonds and electrostatic interactions. These findings could promote the rational design of novel P-CABs. PMID:24845980

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

    PubMed

    Ajitha, Manjaly J; Huang, Kuo-Wei

    2015-12-07

    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.

  2. Effect of amino acid additives on the growth and physical properties of potassium acid phthalate (KAP) crystals

    NASA Astrophysics Data System (ADS)

    Kumaran, A. Elakkina; Kanchana, P.; Sekar, C.

    2012-06-01

    Single crystals of potassium acid phthalate (KAP) have been grown from aqueous solution by slow evaporation technique by adding L-alanine (LA), glycine (Gly) and L-tyrosine (LT) as additives. Powder X-ray diffraction studies confirmed the phase formation and amino acids doping into KAP crystals. The optical absorption studies reveal that the LA doped crystals possess less absorption of visible ray than the pristine, Gly and LT doped KAP crystals. Optical transmission is found to be low in LT doped KAP than in all the other crystals. TG-DTA studies show the decomposition temperatures to be 255 °C, 232 °C, 258 °C and 264 °C for pure, LA, Gly and LT doped KAP crystals respectively. SHG efficiency of LA doped KAP crystal was found to be 1.1 times (31 mV for KDP and 34 mV for LA doped KAP) that of potassium dihydrogen phosphate (KDP) crystal. This is much higher when compared to that of undoped KAP crystal (12 mV). The grown crystals were also subjected to FTIR, microhardness and dielectric studies.

  3. Potassium fulvate as co-interpenetrating agent during graft polymerization of acrylic acid from cellulose.

    PubMed

    Ghazy, Mohamed B M; El-Hai, Farag Abd; Mohamed, Magdy F; Essawy, Hisham A

    2016-10-01

    Grafting polymerization of acrylic acid onto cellulose in presence of potassium fulvate (KF) as a co-interpenetrating agent results enhanced water sorption compared to materials prepared similarly in its absence. The insertion of potassium fulvate (KF) did not affect the grafting process and is thought to proceed in parallel to the graft polymerization via intensive polycondensation reactions of its function groups (-COOH and OH) with COOH of the monomer and OH groups of cellulose. The combination of graft copolymerization and polycondensation reactions is assumed to produce interpenetrating network structure. Fourier transform infrared (FTIR) confirmed successful incorporation within the network structure which is an evidence for formation of interpenetrating network. The obtained structures showed homogeneous uniform surface as revealed by scanning electron microscopy (SEM). The obtained superabsorbent possessed high water absorbency 422 and 48.8g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced water retention even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high content of hydrophilic groups. The new superabsorbents proved to be efficient devices for controlled release of fertilizers which expands their use in agricultural applications.

  4. Special interaction of anionic phosphatidic acid promotes high secondary structure in tetrameric potassium channel.

    PubMed

    Raja, Mobeen

    2014-08-01

    Anionic phosphatidic acid (PA) has been shown to stabilize and bind stronger than phosphatidylglycerol via electrostatic and hydrogen bond interaction with the positively charged residues of potassium channel KcsA. However, the effects of these lipids on KcsA folding or secondary structure are not clear. In this study, the secondary structure analyses of KcsA potassium channel was carried out using circular dichroism spectroscopy. It was found that PA interaction leads to increases in α-helical and β-sheet content of KcsA protein. In PA, KcsA α-helical structure was further stabilized by classical membrane-active cosolvent trifluoroethanol followed by reduction in the β-sheet content indicating cooperative transformation from the β-sheet to an α-helical structure. The data further uncover the role of anionic PA in KcsA folding and provide mechanism by which strong hydrogen bonds/electrostatic interaction among PA headgroup and basic residues on lipid binding domains may induce high helical structure thereby altering the protein folding and increasing the stability of tetrameric assembly.

  5. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates.

    PubMed

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-20

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation.

  6. Influence of anodization parameters on the volume expansion of anodic aluminum oxide formed in mixed solution of phosphoric and oxalic acids

    NASA Astrophysics Data System (ADS)

    Kao, Tzung-Ta; Chang, Yao-Chung

    2014-01-01

    The growth of anodic alumina oxide was conducted in the mixed solution of phosphoric and oxalic acids. The influence of anodizing voltage, electrolyte temperature, and concentration of phosphoric and oxalic acids on the volume expansion of anodic aluminum oxide has been investigated. Either anodizing parameter is chosen to its full extent of range that allows the anodization process to be conducted without electric breakdown and to explore the highest possible volume expansion factor. The volume expansion factors were found to vary between 1.25 and 1.9 depending on the anodizing parameters. The variation is explained in connection with electric field, ion transport number, temperature effect, concentration, and activity of acids. The formation of anodic porous alumina at anodizing voltage 160 V in 1.1 M phosphoric acid mixed with 0.14 M oxalic acid at 2 °C showed the peak volume expansion factor of 1.9 and the corresponding moderate growth rate of 168 nm/min.

  7. Acidic Potassium Permanganate Chemiluminescence for the Determination of Antioxidant Potential in Three Cultivars of Ocimum basilicum.

    PubMed

    Srivastava, Shivani; Adholeya, Alok; Conlan, Xavier A; Cahill, David M

    2016-03-01

    Ocimum basilicum, a member of the family Lamiaceae, is a rich source of polyphenolics that have antioxidant properties. The present study describes the development and application of an online HPLC-coupled acidic potassium permanganate chemiluminescence assay for the qualitative and quantitative assessment of antioxidants in three cultivars of O. basilicum grown under greenhouse conditions. The chemiluminescence based assay was found to be a sensitive and efficient method for assessment of total and individual compound antioxidant potential. Leaves, flowers and roots were found to be rich reserves of the antioxidant compounds which showed intense chemiluminescence signals. The polyphenolics such as rosmarinic, chicoric, caffeic, p-coumaric, m-coumaric and ferulic acids showed antioxidant activity. Further, rosmarinic acid was found to be the major antioxidant component in water-ethanol extracts. The highest levels of rosmarinic acid was found in the leaves and roots of cultivars "holy green" (14.37; 11.52 mM/100 g DW respectively) followed by "red rubin" (10.02; 10.75 mM/100 g DW respectively) and "subja" (6.59; 4.97 mM/100 g DW respectively). The sensitivity, efficiency and ease of use of the chemiluminescence based assay should now be considered for its use as a primary method for the identification and quantification of antioxidants in plant extracts.

  8. Determination of free acid by standard addition method in potassium thiocyanate

    SciTech Connect

    Baumann, E W

    1982-06-01

    The free acid content of solutions containing hydrolyzable ions has been determined potentiometrically by a standard addition method. Two increments of acid are added to the sample in 1M potassium thiocyanate solution. The sample concentration is calculated by solution of three simultaneous Nernst equations. The method has been demonstrated for solutions containing Al/sup 3 +/, Cr/sup 3 +/, Fe/sup 3 +/, Hg/sup 2 +/, Ni/sup 2 +/, Th/sup 4 +/, or UO/sub 2//sup 2 +/ with a metal-to-acid ratio of < 2.5. The method is suitable for determination of 10 ..mu..moles acid in 10 mL total volume. The accuracy can be judged from the agreement of the Nernst slopes found in the presence and absence of hydrolyzable ions. The relative standard deviation is < 2.5%. The report includes a survey of experiments with thermometric, pH, and Gran plot titrations in a variety of complexants, from which the method was evolved. Also included is a literature survey of sixty references, a discussion of the basic measurements, and a complete analytical procedure.

  9. Determination of free acid by standard addition method in potassium thiocyanate

    SciTech Connect

    Not Available

    1981-06-01

    An analytical method for determination of free acidity in all SRP process solutions has been developed. Free acidity was successfully determined in solutions of nitric acid and the nitrates of aluminum, chromium(III), iron(III), mercury(II), nickel(II), thorium, and uranium(VI), at metal-to-acid ratios <2.5. Sample requirements, instrumentation, and mode of operation are similar to those currently used in the Laboratories Department free acid procedures. The simple procedure would be suitable for automation and microprocessor control. The method consists of two additions of known increments of acid into a solution containing the sample aliquot (10 ..mu..moles free acid) and 10 mL 1M potassium thiocyanate. The potential is determined in the initial solution and after each addition with a glass electrode and pH meter. The sample concentration is calculated by solution of three simultaneous Nernst equations. Two programs for this iterative computation are available: one written for the PDP-15 computer and another for a Hewlett-Packard 67 (or 97) programmable calculator. The accuracy of the result is verified by a slope that approximates the theoretical Nernst value. The relative standard deviation is <2.5%. This memorandum includes a survey of experiments with thermometric, pH, and Gran plot titrations in a variety of complexants, from which this particular system and technique logically evolved. The appendix includes a literature survey of sixty references, a discussion of the basic measurements, and a complete analytical procedure. The final step for completion of this RTA is training and consultation at the convenience of the Laboratories Department for demonstration of the method with process samples.

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

    PubMed Central

    Akhtar, Muhammad

    2013-01-01

    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 % CaCO3 for 15 days. Freundlich adsorption isotherms (P = aC b/a) 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 CaCO3. Moreover, at all the levels of CaCO3, 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 CaCO3 contents and quantity of fertilizer to other similar textured soils needs confirmation. PMID:24307878

  11. Optimizing available phosphorus in calcareous soils fertilized with diammonium phosphate and phosphoric acid using Freundlich adsorption isotherm.

    PubMed

    Naeem, Asif; Akhtar, Muhammad; Ahmad, Waqar

    2013-01-01

    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 % CaCO3 for 15 days. Freundlich adsorption isotherms (P = aC(b/a)) 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 CaCO3. Moreover, at all the levels of CaCO3, 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 CaCO3 contents and quantity of fertilizer to other similar textured soils needs confirmation.

  12. Effects of phosphoric acid concentration and etch duration on enamel depth of etch: an in vitro study.

    PubMed

    Legler, L R; Retief, D H; Bradley, E L

    1990-08-01

    In a previous study we reported no significant differences among the shear bond strengths resulting from the application of an orthodontic bonding resin to enamel surfaces etched with three phosphoric acid (H3PO4) concentrations, each for three etch durations. The objective of the current study was to determine the depths of etch on ground enamel surfaces exposed to the nine etching procedures. The facial surfaces of 45 extracted human maxillary permanent central incisors were ground wet on 600-grit silicon carbide paper. Annular adhesive disks of 6 mm outer diameter and 3 mm inner diameter were positioned on the ground enamel surfaces and etched with 10 mm3 of 37%, 15%, and 5% H3PO4 for 60, 30, and 15 seconds, respectively. The calcium concentrations of the etching solutions were determined and the depths of etch calculated. The depths of etch were then measured with a surface profilometer. A stepwise decrease in the calculated depths of etch with decreasing acid concentration and duration of etching was obtained. The calculated etch depths ranged from 27.1 microns by etching with 37% H3PO4 for 60 seconds to 3.5 microns by etching with 5% H3PO4 for 15 seconds. The measured depths of etch followed a similar pattern. A highly significant correlation between calculated and measured depths of etch was obtained.

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

    PubMed

    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.

  14. Preparation and physical properties of (PVA)0.7(NaBr)0.3(H3PO4)xM solid acid membrane for phosphoric acid – Fuel cells

    PubMed Central

    Ahmad, F.; Sheha, E.

    2012-01-01

    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 (PVA)0.7(NaBr)0.3(H3PO4)xM 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 (PVA)0.7(NaBr)0.3(H3PO4)xM solid acid membrane is promising for intermediate temperature phosphoric acid fuel cell applications. PMID:25685413

  15. Effect of nanolayering of calcium salts of phosphoric acid ester monomers on the durability of resin-dentin bonds.

    PubMed

    Tian, Fu-Cong; Wang, Xiao-Yan; Huang, Qi; Niu, Li-Na; Mitchell, Jan; Zhang, Zheng-Yi; Prananik, Chandrani; Zhang, Lu; Chen, Ji-Hua; Breshi, Lorenzo; Pashley, David H; Tay, Franklin R

    2016-07-01

    To investigate the contribution of nanolayering on resin-dentin bond durability, two phosphoric acid ester resin monomers, 10-methacryloyloxy-decyl-dihydrogen-phosphate (10-MDP) or its analog, methacryloyloxy-penta-propyleneglycol-dihydrogen-phosphate (MDA), were examined for their affinity for mineralized dentin powder in a column chromatography setup. Hydroxyapatite (HA) powder was dispersed in experimental primers consisting of 10-MDP or MDA solvated in ethanol/water and examined with FTIR, (31)P MAS-NMR and XPS. Light-curable 10-MDP or MDA primers were used for bonding to dentin, and examined after 24h or one-year of water-aging by TEM for evidence of nanolayering, and for microtensile bond strength evaluation. Primer-bonded dentin was examined by thin-film XRD to identify short-range order peaks characteristic of nanolayering of resin monomer-Ca salts. Although 10-MDP had better affinity for mineralized dentin than MDA, both monomers completely eluted from the mineralized dentin powder column using ethanol-water as mobile phase, indicating that the adsorption processes were reversible. This finding was supported by chemoanalytic data. XRD of 10-MDP-bonded dentin showed three diffraction peaks hat were absent from MDA-bonded dentin. Nanolayering was identified by TEM in 10-MDP-bonded dentin, but not in MDA-bonded dentin. Significant drop in bond strength (in MPa) was observed for both groups after one-year of water-aging compared with 24-h: 10-MDP group from 48.3±6.3 to 37.4±4.6; MDA group from 50.7±5.0 to 35.7±3.8 (P<0.05), with no significant difference between the two groups at the same time-point. Because both functional monomer-primed, resin-bonded dentin exhibited similar bond strength decline after water-aging, presence of nanolayering is unlikely to contribute to the overall resin-dentin bond durability. The durability of resin-dentin bonds in 10-MDP containing self-etching adhesives has been anecdotally attributed to the presence of nanolayering of

  16. Chemiluminescence detection of cannabinoids and related compounds with acidic potassium permanganate.

    PubMed

    Holland, Brendan J; Francis, Paul S; Li, Bingshan; Tsuzuki, Takuya; Adcock, Jacqui L; Barnett, Neil W; Conlan, Xavier A

    2012-01-01

    This is the first report of chemiluminescence from the reaction of cannabinoids with acidic potassium permanganate, which we have applied to the high performance liquid chromatography (HPLC) determination of cannabidiol (CBD) in industrial-grade hemp. The intensities of the light-producing reactions with two commercially available cannabinoid standards were compared to that of seven model phenolic analytes. Resorcinol, representing the parent phenolic moiety of the cannabinoid class, was shown to react with the permanganate reagents in a manner more similar to phenol than to its hydroxyphenol positional isomers, pyrocatechol and hydroquinone. Alkyl substituents on the phenolic ring, however, have a considerable impact on emission intensity that is dependent upon the position of the groups and the composition of the permanganate reagent. This analytical approach has potential for the determination of other cannabinoids including Δ(9) -tetrahydrocannabinol in drug-grade cannabis. Copyright © 2012 John Wiley & Sons, Ltd.

  17. Characterization of potassium bromide crystals grown in the aqueous solution of picric acid

    NASA Astrophysics Data System (ADS)

    Maheswari, J. Uma; Krishnan, C.; Kalyanaraman, S.; Selvarajan, P.

    2016-12-01

    Potassium bromide crystals were grown in the aqueous solution of picric acid by slow evaporation technique at room temperature. X-ray Diffraction (XRD) analysis ensures that the grown sample is in Fm3m space group and FCC structure. Energy Dispersive X-ray Spectroscopy (EDX) reveals the presence of elements in the title compound. UV-Vis-NIR spectrum reveals that the grown sample is a promising nonlinear optical (NLO) material. FTIR analysis confirms the functional groups present in the sample. The thermogravimetric (TG) and differential thermogravimetric (DTA) analyses ensure that the sample material is thermally stable up to 160 °C. The second harmonic efficiency of the sample is 1.3 times greater than that of standard KDP. The mechanical strength of the grown sample is estimated by Vickers microhardness tester. The electrical properties were investigated by impedance analysis and the results of various studies of the grown crystals are discussed.

  18. Measuring and predicting the diffraction properties of cylindrically bent potassium acid phthalate, KAP(001), crystals

    NASA Astrophysics Data System (ADS)

    Haugh, M. J.; Jacoby, K. D.

    2017-02-01

    This report presents the results from measuring the X-ray diffraction properties of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two measurement methods. One method used a diode type X-ray source and a dual goniometer analysis system, utilizing a flat, perfect KAP(001) crystal as the monochromator. The second method used a synchrotron source and dual crystal Si(111) monochromator. Bent crystals are used in X-ray spectrometers as dispersion elements. These crystals are bent into a circular cylinder section, and this bending can alter the rocking curve properties. The crystal rocking curves were measured for spectral energies ranging from 1250 to 4500 eV. A multi-lamellar model was compared to the measurements and showed good quantitative agreement. This provides a valuable tool for predicting the changes to the KAP (001) for any radius of curvature when the crystal is bent into a cylindrical section.

  19. Liver injury after aluminum potassium sulfate and tannic acid treatment of hemorrhoids

    PubMed Central

    Yoshikawa, Kenichi; Kawashima, Reimi; Hirose, Yuki; Shibata, Keiko; Akasu, Takafumi; Hagiwara, Noriko; Yokota, Takeharu; Imai, Nami; Iwaku, Akira; Kobayashi, Go; Kobayashi, Hirohiko; Kinoshita, Akiyoshi; Fushiya, Nao; Kijima, Hiroyuki; Koike, Kazuhiko; Saruta, Masayuki

    2017-01-01

    We are reporting a rare case of acute liver injury that developed after an internal hemorrhoid treatment with the aluminum potassium sulfate and tannic acid (ALTA) regimen. A 41-year-old man developed a fever and liver injury after undergoing internal hemorrhoid treatment with a submucosal injection of ALTA with lidocaine. The acute liver injury was classified clinically as hepatocellular and pathologically as cholestastic. We could not classify the mechanism of injury. High eosinophil and immunoglobulin E levels characterized the injury, and a drug lymphocyte stimulation test was negative on postoperative day 25. Fluid replacement for two weeks after hospitalization improved the liver injury. ALTA therapy involves injecting chemicals into the submucosa, from the rectum to the anus, and this is the first description of a case that developed a severe liver disorder after this treatment; hence, an analysis of future cases as they accumulate is desirable. PMID:28785156

  20. A Neat Trick Using Oxalic Acid Dihydrate and Potassium Permanganate and Other Experiments with Small Organic Amine or Oxygenated Compounds

    ERIC Educational Resources Information Center

    Kelland, Malcolm A.

    2011-01-01

    Solid potassium permanganate (KMnO[subscript 4]) is shown to react in a variety of ways with small organic amines or oxygenated compounds depending on whether they are liquids or solids and whether water is present. In particular, its reaction with solid oxalic acid dihydrate can be initiated by the moisture in one's breath, making an intriguing…

  1. Bacterial flora of skin of processed broiler chickens after successive washings in mixtures of potassium hydroxide and lauric acid

    USDA-ARS?s Scientific Manuscript database

    Changes in the size of the populations of different groups of bacteria in the normal flora of the skin of processed broilers were examined after each of five consecutive washings with mixtures of potassium hydroxide (KOH) and lauric acid (LA). Skin from commercially processed broiler carcasses was ...

  2. A Neat Trick Using Oxalic Acid Dihydrate and Potassium Permanganate and Other Experiments with Small Organic Amine or Oxygenated Compounds

    ERIC Educational Resources Information Center

    Kelland, Malcolm A.

    2011-01-01

    Solid potassium permanganate (KMnO[subscript 4]) is shown to react in a variety of ways with small organic amines or oxygenated compounds depending on whether they are liquids or solids and whether water is present. In particular, its reaction with solid oxalic acid dihydrate can be initiated by the moisture in one's breath, making an intriguing…

  3. Effect of foliar and soil application of potassium fertilizer on soybean seed protein, oil, fatty acids, and minerals

    USDA-ARS?s Scientific Manuscript database

    The objective of this research was to evaluate the effectiveness of soil and foliar application of potassium (K) on leaf and seed mineral concentration levels, and seed composition (protein, oil, fatty acids, and minerals). Soybean cultivar (Pioneer 95470) of maturity group 5.7 was grown in a repeat...

  4. Usefulness of vonoprazan, a potassium ion-competitive acid blocker, for primary eradication of Helicobacter pylori

    PubMed Central

    Yamada, Shinya; Kawakami, Takumi; Nakatsugawa, Yoshikazu; Suzuki, Takahiro; Fujii, Hideki; Tomatsuri, Naoya; Nakamura, Hideki; Sato, Hideki; Okuyama, Yusuke; Kimura, Hiroyuki; Yoshida, Norimasa

    2016-01-01

    AIM To investigate usefulness of triple therapy with vonoprazan, a potassium ion-competitive acid blocker and antibiotics, for Helicobacter pylori (H. pylori) eradication. METHODS The H. pylori eradication rate was examined in 2507 patients (2055 undergoing primary eradication and 452 undergoing secondary eradication, excluding patients with subtotal gastrectomy) at the Japanese Red Cross Kyoto Daiichi Hospital from March 2013 to September 2015. For patients treated from March 2013 to February 2015, a proton pump inhibitor (PPI) was used to reduce acid secretion, while vonoprazan was used after March 2015. The success rates of the 2 regimens (PPI + amoxicillin + clarithromycin/metronidazole, or vonoprazan + amoxicillin + clarithromycin/metronidazole) were compared. RESULTS The success rate of primary H. pylori eradication was significantly higher in the vonoprazan group. When stratified by the underlying disease, a significant increase of the H. pylori eradication rate was observed in patients with chronic gastritis. A significantly lower H. pylori eradication rate was observed in younger patients compared to older patients in the PPI group, but there was no difference according to age in the vonoprazan group. On the other hand, the success rate of secondary eradication was similar at approximately 90% in both groups. CONCLUSION Vonoprazan is very useful for primary eradication of H. pylori, and may become a first-line acid secretion inhibitor instead of PPIs. PMID:27867688

  5. Use of potassium permanganate for iron and manganese removal from acid mine drainage

    SciTech Connect

    Boll, J.E.; Deshinsky, G.

    1985-12-09

    Surface and deep shaft coal mining operations find it difficult to meet Environmental Protection Agency (EPA) standards concerning acid, iron and manganese in drainage waters. Correcting the acid and iron problem is relatively simple, but effectively controlling manganese is more difficult. The best way to remove manganese is by chemical oxidation. A common treatment method is pH adjustment with lime or soda ash. This practice neutralizes the acid and removes most of the iron by forming an insoluble precipitate. The amount of lime or soda ash needed to remove manganese raises the pH beyond the acceptable range of 6-9. Potassium permanganate (KMnO/sub 4/) can be used to oxidize the dissolved manganese to an insoluble manganese precipitate. It can also oxidize any residual iron. The adjusted pH reduces unnecessary consumption of permanganate needed to oxidize manganese and meets EPA standards. It reacts on contact producing an insoluble manganese dioxide (MnO/sub 2/). The MnO/sub 2/ supplements the oxidation with a settling effect. Permanganate can be applied at all pHs, with faster results at neutral or slightly alkaline levels. Its use for iron and manganese removal is very attractive because the reactions are complete, rapid, and require only a minimal amount of chemicals. Laboratory evaluation and field case histories will be discussed in the paper. 3 figures.

  6. Identification and localization of an arachidonic acid-sensitive potassium channel in the cochlea.

    PubMed

    Sokolowski, Bernd H A; Sakai, Yoshihisa; Harvey, Margaret C; Duzhyy, Dmytro E

    2004-07-14

    Receptor cells of the auditory and vestibular end organs of vertebrates acquire various types of potassium channels during development. Their expression and kinetics can differ along the tonotopic axis as well as in different cell types of the sensory epithelium. These variations can play a crucial role in modulating sensory transduction and cochlear tuning. Whole-cell tight-seal recordings of isolated hair cells revealed the presence of an arachidonic acid-sensitive A-type channel in the short (outer) hair cells of the chicken cochlea. This polyunsaturated fatty acid blocked the A-current, thereby increasing the amplitude and duration of the voltage response in these cells. We identified the gene encoding this channel as belonging to a member of the Shal subfamily, Kv4.2. Expression of the recombinant channel shows half-activation and inactivation potentials shifted to more positive values relative to native channels, suggesting that the native channel is coexpressed with an accessory subunit. RT-PCR revealed that transcription begins early in development, whereas in situ hybridization showed mRNA expression limited to the intermediate and short hair cells located in specific regions of the adult cochlea. Additional localization, using immunofluorescent staining, revealed clustering in apical-lateral regions of the receptor cell as well as in the cochlear ganglion. These experiments provide evidence that in addition to membrane proteins modulating excitation in these receptor cells, fatty acids contribute to the coding of auditory stimuli via these channels.

  7. 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.

    PubMed

    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 (H3PO4) 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.

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

    SciTech Connect

    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.

  9. Effect of sodium sulfite, carboxylic monomer, and phosphoric acid etching on bonding of tri-n-butylborane initiated resin to human enamel.

    PubMed

    Nogawa, Hiroshi; Koizumi, Hiroyasu; Akazawa, Nobutaka; Hiraba, Haruto; Nakamura, Mitsuo; Matsumura, Hideo

    2015-03-01

    The purpose of the present study is evaluation of bonding durability of tri-n-butylborane (TBB) initiated resin without 4-methacryloyloxyethyl trimellitate anhydride (4-META) joined to human enamel. Ground human enamel was bonded with TBB resin under six surface conditions: 1) as ground, 2) primed with Teeth Primer, 3) sodium sulfite solution, 4) 4-META solution, 5) acetone-water, and 6) phosphoric acid etching. Pre- and post-thermocycling bond strengths and change in strength after thermocycling were compared. Etching enamel with 35-45% phosphoric acid enhanced bonding durability between enamel and TBB-initiated resin. Priming with Teeth Primer or 4-META solution improved bond strength between enamel and TBB-initiated resin. Sodium sulfite had little effect on enamel bonding in the present bonding systems.

  10. Extraction and isolation of TPE from other elements on ion exchangers in aqueous and aqueous-organic solutions of phosphoric acid

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Stepushkina, V.V.

    1988-07-01

    The behavior of Am-Es and other actinides on anion and cation exchange resins in aqueous and aqueous-organic solutions of phosphoric acid has been studied in a wide range of concentration of various components of the solution. The sorptivity of transplutonium elements (TPE) on anion exchangers from dilute H/sub 3/PO/sub 4/ with a concentration less than or equal to 1 M in presence of organic solvents (alcohols, ketones, etc.) and on cation exchangers from concentrated H/sub 3/PO/sub 4/ has been found to be significant. The possibility of use of phosphoric acid solutions for isolation of TPE from Th, Pa, U, Np, Pu, and Zr and separation of TPE in different oxidation states in presence of a high-purity oxidant has been shown.

  11. Fuel ethanol production from corn stover under optimized dilute phosphoric acid pretreatment and enzymatic hydrolysis

    USDA-ARS?s Scientific Manuscript database

    Ethanol is a renewable oxygenated fuel. Dilute acid pretreatment is a promising pretreatment technology for conversion of lignocellulosic biomass to fuel ethanol. Generation of fermentable sugars from corn stover involves pretreatment and enzymatic saccharification. Pretreatment is crucial as nat...

  12. Chiral phosphoric acid catalyzed highly enantioselective Friedel-Crafts alkylation reaction of C3-substituted indoles to β,γ-unsaturated α-ketimino esters.

    PubMed

    Bi, Bo; Lou, Qin-Xin; Ding, Yu-Yang; Chen, Sheng-Wei; Zhang, Sha-Sha; Hu, Wen-Hui; Zhao, Jun-Ling

    2015-02-06

    A highly enantioselective C2 Friedel-Crafts alkylation reaction of 3-substituted indoles to β,γ-unsaturated α-ketimino esters has been developed. This reaction was efficiently catalyzed by a chiral phosphoric acid catalyst. The corresponding C2-substituted indole derivatives, bearing an α-ketimino ester motif, were obtained in moderate to high yields (up to 93%) and with high enantioselectivities (up to >99% ee).

  13. 40 CFR 721.6120 - Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid, 1,2-eth-a-ne-diyl tet-ra-kis(2-chloro-1-meth-yl-ethyl) ester. 721.6120 Section 721.6120 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

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

    PubMed

    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.

  15. Regio-, Diastereo-, and Enantioselective Nitroso-Diels-Alder Reaction of 1,3-Diene-1-carbamates Catalyzed by Chiral Phosphoric Acids.

    PubMed

    Pous, Jonathan; Courant, Thibaut; Bernadat, Guillaume; Iorga, Bogdan I; Blanchard, Florent; Masson, Géraldine

    2015-09-23

    Chiral phosphoric acid-catalyzed asymmetric nitroso-Diels-Alder reaction of nitrosoarenes with carbamate-dienes afforded cis-3,6-disubstituted dihydro-1,2-oxazines in high yields with excellent regio-, diastereo-, and enantioselectivities. Interestingly, we observed that the catalyst is able not only to control the enantioselectivity but also to reverse the regioselectivity of the noncatalyzed nitroso-Diels-Alder reaction. The regiochemistry reversal and asynchronous concerted mechanism were confirmed by DFT calculations.

  16. Anodic luminescence, structural, photoluminescent, and photocatalytic properties of anodic oxide films grown on niobium in phosphoric acid

    NASA Astrophysics Data System (ADS)

    Stojadinović, Stevan; Tadić, Nenad; Radić, Nenad; Stefanov, Plamen; Grbić, Boško; Vasilić, Rastko

    2015-11-01

    This article reports on properties of oxide films obtained by anodization of niobium in phosphoric acid before and after the dielectric breakdown. Weak anodic luminescence of barrier oxide films formed during the anodization of niobium is correlated to the existence of morphological defects in the oxide layer. Small sized sparks generated by dielectric breakdown of formed oxide film cause rapid increase of luminescence intensity. The luminescence spectrum of obtained films on niobium under spark discharging is composed of continuum radiation and spectral lines caused by electronic spark discharging transitions in oxygen and hydrogen atoms. Oxide films formed before the breakdown are amorphous, while after the breakdown oxide films are partly crystalline and mainly composed of Nb2O5 hexagonal phase. The photocatalytic activity of obtained oxide films after the breakdown was investigated by monitoring the degradation of methyl orange. Increase of the photocatalytic activity with time is related to an increase of oxygen vacancy defects in oxide films formed during the process. Also, higher concentration of oxygen vacancy defects in oxide films results in higher photoluminescence intensity.

  17. Ultra-sensitive detection of zinc oxide nanowires using a quartz crystal microbalance and phosphoric acid DNA

    NASA Astrophysics Data System (ADS)

    Jang, Kuewhan; You, Juneseok; Park, Chanhoo; Park, Hyunjun; Choi, Jaeyeong; Choi, Chang-Hwan; Park, Jinsung; Lee, Howon; Na, Sungsoo

    2016-09-01

    Recent advancements of nanomaterials have inspired numerous scientific and industrial applications. Zinc oxide nanowires (ZnO NWs) is one of the most important nanomaterials due to their extraordinary properties. However, studies performed over the past decade have reported toxicity of ZnO NWs. Therefore, there has been increasing demand for effective detection of ZnO NWs. In this study, we propose a method for the detection of ZnO NW using a quartz crystal microbalance (QCM) and DNA probes. The detection method is based on the covalent interaction between ZnO NWs and the phosphoric acid group of single-stranded DNA (i.e., linker DNA), and DNA hybridization between the linker DNA and the probe DNA strand on the QCM electrode. Rapid, high sensitivity, in situ detection of ZnO NWs was demonstrated for the first time. The limit of detection was 10-4 μg ml-1 in deionized water, which represents a sensitivity that is 100000 times higher than the toxic ZnO NW concentration level. Moreover, the selectivity of the ZnO NW detection method was demonstrated by comparison with other types of nanowires and the method was able to detect ZnO NWs in tap water sensitively even after stored for 14 d in a refrigerator. The performance of our proposed method was sufficient to achieve detection of ZnO NW in the ‘real-world’ environment.

  18. Valoniopsis pachynema Extract as a Green Inhibitor for Corrosion of Brass in 0.1 N Phosphoric Acid Solution

    NASA Astrophysics Data System (ADS)

    Selva Kumar, R.; Chandrasekaran, V.

    2016-04-01

    The effect of marine alga Valoniopsis pachynema extract on corrosion inhibition of brass in phosphoric acid was investigated by weight-loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy studies. The inhibition efficiency is found to increase with increasing concentration of extract and decreases with rise in temperature. The activation energy, thermodynamic parameters (free energy, enthalpy, and entropy change) and kinetic parameters (rate constant and half-life) for inhibition process were calculated. These thermodynamic and kinetic parameters indicate a strong interaction between the inhibitor and the brass surface. The inhibition is assumed to occur via adsorption of inhibitor molecules on brass surface, which obeys Temkin adsorption isotherm. The adsorption of inhibitor on the brass surface is exothermic, physical, and spontaneous, and follows first-order kinetics. The polarization measurements showed that the inhibitor behaves as a mixed type inhibitor and the higher inhibition surface coverage on the brass was predicted. Inhibition efficiency values were found to show good trend with weight-loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy studies. Surface study techniques (FT-IR and SEM) were carried out to ascertain the inhibitive nature of the algal extract on the brass surface.

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

    PubMed

    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 H3PO4 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, H3PO4 proportion, and time. H3PO4 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 H3PO4 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 H3PO4 usage and maximizing glucose yield, the optimized pretreatment conditions was 40 °C, 2.0 h, and H3PO4 proportion of 70.2 % (H2O2 proportion of 5.2 %), by which glucose yielded 299 mg/g wheat straw (946.2 mg/g cellulose) after 72-h enzymatic hydrolysis.

  20. Extraction of transplutionium and rare-earth elements, molybdenum and iron with zirconium salt of dibutyl phosphoric acid

    NASA Astrophysics Data System (ADS)

    Zilberman, B. Ya.; Fedorov, Yu. S.; Shmidt, O. V.; Goletsky, N. D.; Sukhareva, S. Yu.; Puzikov, E. A.; Suglobov, D. N.; Mashirov, L. G.; Choppin, G. R.

    2003-01-01

    Zirconium salt of dibutyl phosphoric acid (ZS-HDBP) dissolved in dilute tributyl phosphate (TBP) is proposed as a solvent for separation of transplutonium and rare-earth elements (TPE, RE), including yttrium, from high-level waste in the presence of molybdenum and iron. The optimum HDBP:Zr ratio is 9 for RE and TPE extraction and is 12.5 for Mo. IR spectra indicate formation of Zr(DBP)4(HDBP)4 complex as a base of solvation. HNO3 depresses RE and TPE extraction, while Mo extraction is characterised by a minimum at 2.5 mol/L HNO3. Presence of TBP in the solvent, independently of the used diluent, leads to reduction of the distribution coefficients, but ZS-HDBP extraction capacity for the above elements is increased, as well as solubility of their solvates. Two types of complexes M(DBP)3 and MNO3(DBP)2 are formed at RE and TPE extraction by ZS-HDBP in dilute TBP. Molybdenum extraction is based both on cation exchange and on Mo solvation with HDBP as a neutral ligand. Iron extraction is formally similar to that of Mo, being influenced by the latter if both metals are present in the solution.