The Photolysis of Aqueous-Solutions of Potassium Hexacyanoferrate(III)

1986 ◽  
Vol 39 (9) ◽  
pp. 1411 ◽  
Author(s):  
MW Fuller ◽  
KMF Lebrocq ◽  
E Leslie ◽  
IR Wilson
Keyword(s):  
Aqueous Solutions ◽  
Quantum Yields ◽  
Alkaline Solutions ◽  
Potassium Hexacyanoferrate ◽  
Thermal Reactions ◽  
Acidic Solutions

The photolysis of aqueous solutions of potassium hexacyanoferrate(III) at 254 and 366 nm forms aqua- or hydroxo-pentacyanoferrate(III) in both acidic and alkaline solutions, with quantum yields between 0.02 and 0.06. Subsequent thermal reactions form the decacyanodiferrate(III) and/or decacyanodiferrate(III,II) species, especially in weakly acidic solutions, and, in alkaline solutions, may precipitate hydrated iron(III) oxides.

scholarly journals Boron removal from aqueous solutions by a polyethylenimine-epichlorohydrin resin

2018 ◽  
Vol 83 (2) ◽  
pp. 251-264 ◽  
Author(s):  
Sofia Sarri ◽  
Panagiotis Misaelides ◽  
Dimitrios Zamboulis ◽  
Jolanta Warchoł
Keyword(s):  
Aqueous Solutions ◽  
Boron Concentration ◽  
Kinetic Studies ◽  
Alkaline Solutions ◽  
Competitive Sorption ◽  
Boron Removal ◽  
Boron Uptake ◽  
Acidic Solutions ◽  
Ph Values ◽  
Batch Technique

The use of a polyethylenimine?epichlorohydrin resin for the boron removal from aqueous solutions (boron concentration: 100?5000 mg L-1) of non-adjusted and pre-adjusted pH (pHnat, pHinit 8.0, 9.0 and 10.0) aqueous solutions was investigated using a batch technique. The boron concentration in the solutions after sorption was determined photometrically. The results indicated that the pH-dependent boron uptake was related to the protonation/deprotonation of the surface functional groups of the resin and to the boron speciation in solutions of different pH values. The maximum boron sorption capacity observed in solutions of pH 9.0 was 55 mg g-1 exceeding the majority of other commercial or alternative sorbents. Five empirical adsorption equations (Freundlich, Langmuir, Redlich?Peterson, Langmuir?Freundlich and Toth) were applied to the modelling of the boron adsorption equilibrium. The modelling results identified the homogenous boron sorption from acidic and heterogeneous from alkaline solutions. At alkaline pH, the system non-ideality can originate either from the different binding mechanism or from the competitive sorption of different boron species. The homogenous type boron sorption from acidic solutions was further confirmed by kinetic studies

The photolysis of aqueous systems at 1849 Å II. Solutions containing Cl - , Br - , SO 2- 4 or OH - ions

1965 ◽  
Vol 287 (1410) ◽  
pp. 312-327 ◽  
Keyword(s):  
Aqueous Solutions ◽  
Root Mean Square ◽  
Quantum Yields ◽  
Alkaline Solutions ◽  
Mean Square ◽  
Aqueous Systems ◽  
Extinction Coefficients ◽  
Chain Oxidation ◽  
Oxidation Of Methanol ◽  
A Chain

Quantum yields of nitrogen and hydrogen are recorded for the photolysis at 1849 Å of aqueous solutions of NaCl, KBr, Na 2 SO 4 , NaOH or HCl containing N 2 O or CH 3 OH or both. It is concluded: (i) That the extinction coefficients and quantum yields of hydrated electron formation are—Cl - 3800± 300m -1 cm -1 and 0.43±0.02; Br - , 13000 ± 1000 M -1 cm -1 and 0.34± 0.02; SO 4- 2 , 260 ± 30m -1 cm -1 and 0.71 ±0.04 and OH - , 3600±600 M -1 cm -1 and 0.11. (ii) That k ( e - aq +H + ) = (1.49 ± 0.16) x k ( e - sq. +N 2 O). (iii) That in alkaline solutions a chain oxidation of methanol by N 2 O can occur, (iv) That the application of the Noyes (1955) equation leads to unacceptably large values of the root mean square diffusive displacement.

scholarly journals Electrocatalysis of the HER in acid and alkaline media

2013 ◽  
Vol 78 (12) ◽  
pp. 2007-2015 ◽  
Author(s):  
Nemanja Danilovic ◽  
Ram Subbaraman ◽  
Dusan Strmcnik ◽  
Vojislav Stamenkovic ◽  
Nenad Markovic
Keyword(s):  
Catalytic Decomposition ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Water Molecules ◽  
Bifunctional Catalysts ◽  
High Coverage ◽  
Acidic Solutions ◽  
Noble Metal Catalysts ◽  
Alkaline Environments ◽  
Decomposition Of Water

Trends in the HER are studied on selected metals (M= Cu, Ag, Au, Pt, Ru, Ir, Ti) in acid and alkaline environments. We found that with the exception of Pt, Ir and Au, due to high coverage by spectator species on non-noble metal catalysts, experimentally established positions of Cu , Ag, Ru and Ti in the observed volcano relations are still uncertain. We also found that while in acidic solutions the M-Hupd binding energy most likely is controlling the activity trends, the trends in activity in alkaline solutions are controlled by a delicate balance between two descriptors: the M-Had interaction as well as the energetics required to dissociate water molecules. The importance of the second descriptor is confirmed by introducing bifunctional catalysts such as M modified by Ni(OH); e.g. while the latter serves to enhance catalytic decomposition of water, the metal sites are required for collecting and recombining the produced hydrogen intermediates.

scholarly journals Formation of carboxylic acids during degradation of monosaccharides

2008 ◽  
Vol 26 (No. 2) ◽  
pp. 113-131 ◽  
Author(s):  
O. Novotný ◽  
K. Cejpek ◽  
J. Velíšek
Keyword(s):  
Free Radicals ◽  
Aqueous Solutions ◽  
Carboxylic Acids ◽  
Sodium Hydroxide Solution ◽  
Model Systems ◽  
Alkaline Solutions ◽  
Hydroxycarboxylic Acids ◽  
Acid Type ◽  
Cannizzaro Reaction ◽  
Benzilic Acid

The formation of low molecular carboxylic and hydroxycarboxylic acids as well as sugar and deoxysugar acids from monosaccharides (D-glucose, D-fructose, D-arabinose, DL-glyceraldehyde, and 1,3-dihydroxyacetone) was studied in three different model systems: aqueous and alkaline solutions of potassium peroxodisulfate (K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>), and sodium hydroxide solution. In total, 3 low molecular carboxylic acids (formic, acetic and propionic), 24 hydroxycarboxylic acids, and 12 corresponding lactones were identified and quantified by GC/MS. Formic, acetic, and propionic acids were isolated by extraction with diethyl ether and directly analysed by GC/MS; hydroxycarboxylic acids and their lactones were monitored as their trimethylsilylated derivatives using the same method. Formic, acetic, L-lactic, glycollic, DL-2,4-dihydroxybutanoic acids and aldonic acids derived from the parent sugars were the most abundant compounds in all model systems. Within the models investigated, the yield of carboxylic acids and hydroxycarboxylic acids (together with their lactones) ranged between 9.3–22.2% (n/n) and between 3.6–116.9% (n/n), respectively. The amount of acids was significantly lower in aqueous solutions of K<sub>2</sub>S<sub>2</sub>O<sub>8</sub> than in the alkaline solutions. The data obtained indicate that lower carboxylic acids are formed by both subsequent reactions (oxidation and/or intramolecular Cannizzaro reaction) of the sugar fragmentation products and direct decomposition of some intermediates such as uloses or hydroperoxides derived from the parent sugars. The acids possessing the original sugar skeleton are formed as a result of sugar oxidation or benzilic acid type rearrangement of deoxyuloses. Lower acids may also be formed by a recombination of free radicals.

Eine schnelle Methode zur quantitativen Abtrennung von Chlor und Brom aus sauren wäßrigen Lösungen / A Rapid Method for the Quantitative Elimination of Chlorine or Bromine from Aqueous Acidic Solutions

1988 ◽  
Vol 43 (1) ◽  
pp. 134
Author(s):  
Wolfram Baumgärtner ◽  
Youssef A. Gawargious ◽  
Klaus Brodersen
Keyword(s):  
Aqueous Solutions ◽  
Rapid Method ◽  
Dilute Solution ◽  
Acidic Solutions

Abstract The quantitative elimination of chlorine and bromine from acidic aqueous solutions was achieved through extraction with a dilute solution of styrene in CCl4 .

The Photolysis in Acidic Aqueous Solutions of the Monooxalato-bisethylenediamine Chromium(III) Cation and the Bisoxalatomonoethylenediamine Chromate(III) Anion: Photolysis Modes and Quantum Yields

1971 ◽  
Vol 49 (3) ◽  
pp. 375-383 ◽  
Author(s):  
A. D. Kirk ◽  
K. C. Moss ◽  
J. G. Valentin
Keyword(s):  
Quantum Yield ◽  
Aqueous Solutions ◽  
Quantum Yields ◽  
Ligand Field ◽  
Intersystem Crossing ◽  
Empirical Correlations ◽  
Complex Ions ◽  
Ethylenediamine Complex ◽  
Ethylenediamine Ligand ◽  
Ph Range

The photolysis reactions of the complex ions [Cr(en)2ox]+ and [Cren(ox)2]− have been studied in the pH range 1 → 3 and at temperatures from 0 to 25 °C. It has been found that both ions photoaquate to a monodentate protonated ethylenediamine complex which then undergoes further aquation thermally with loss of the ethylenediamine ligand. Quantum yields for these aquations were measured for irradiation into the ligand field bands, the values obtained being 0.18 and 0.02, respectively. The results are discussed in terms of known empirical correlations for Cr(III) complexes. Assuming these reactions may occur from the 4T2g state as precursor, arguments are presented that the correlation between quantum yield and ΔE may depend on mixing of the 4T2g and 2Eg states, and its effect on the intersystem crossing rate constant.

Mild electrochemical oxidation of zeolite templated carbon in acidic solutions, as a way to boost its charge storage properties in alkaline solutions

Carbon ◽  
2018 ◽  
Vol 138 ◽  
pp. 369-378 ◽  
Author(s):  
Milica Vujković ◽  
Danica Bajuk-Bogdanović ◽  
Ljiljana Matović ◽  
Marija Stojmenović ◽  
Slavko Mentus
Keyword(s):  
Electrochemical Oxidation ◽  
Alkaline Solutions ◽  
Charge Storage ◽  
Acidic Solutions ◽  
Storage Properties ◽  
Templated Carbon

Polarization of Copper in Acidic and Alkaline Solutions

CORROSION ◽  
1971 ◽  
Vol 27 (9) ◽  
pp. 382-385 ◽  
Author(s):  
C P. KIM ◽  
KEN NOBE
Keyword(s):  
Corrosion Rate ◽  
Hydrogen Evolution ◽  
Reaction Order ◽  
Electrochemical Reaction ◽  
Ph Dependence ◽  
Alkaline Solutions ◽  
Hydrogen Ions ◽  
Acidic Solutions ◽  
Copper Dissolution ◽  
Tafel Slopes

Abstract The polarization behavior of copper in acidic and alkaline solutions has been investigated. The cathodic Tafel slopes of copper in acidic solutions for hydrogen evolution by discharge of hydrogen ions were approximately 112 mv. The electrochemical reaction order for this reaction with respect to the concentration of hydrogen ions was one-half. For alkaline solutions, the Tafel slopes of the hydrogen evolution reaction were 180 mv and the rates of this reaction were independent of pH. The anodic Tafel slopes for copper dissolution in acidic solutions were 30 mv. The rate of anodic dissolution was increased by increasing the concentration of hydroxyl ions and the reaction order was about one-half. The pH dependence of the corrosion rate of copper in solutions of pH 0.35 to 5.8 was d log icorr/d PH = −0.4.

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