THE PHOTOCHEMICAL EVOLUTION OF HYDROGEN FROM AQUEOUS SOLUTIONS OF FERROUS IONS. PART I. THE REACTION MECHANISM AT LOW pH

1962 ◽  
Vol 66 (7) ◽  
pp. 1258-1264 ◽  
Author(s):  
Joshua Jortner ◽  
Gabriel Stein
Keyword(s):  
Reaction Mechanism ◽  
Aqueous Solutions ◽  
Low Ph ◽  
Ferrous Ions

scholarly journals Comparison of liver glycosylasparaginases from six vertebrates

1992 ◽  
Vol 282 (3) ◽  
pp. 891-897 ◽  
Author(s):  
O K Tollersrud ◽  
N N Aronson
Keyword(s):  
Amino Acids ◽  
Reaction Mechanism ◽  
Basic Structure ◽  
Low Ph ◽  
Beta Subunit ◽  
Beta Subunits ◽  
Species Identity ◽  
Closely Related Species ◽  
Human Enzyme ◽  
Specific Antisera

Structural and physical properties of glycosylasparaginase (EC 3.5.1.26) from the livers of human, pig, cow, rat, mouse and chicken were compared. The enzyme in all species had a common basic structure of two N-glycosylated subunits of about 24 (alpha) and 20 (beta) kDa joined by non-covalent forces. Subunit-specific antisera against the rat glycosylasparaginase bound specifically and sensitively to the corresponding subunits from all species. Identity of 80% of the amino acids was found between the N-terminal sequences of corresponding pig and rat glycosylasparaginase alpha- and beta-subunits and the deduced sequence from a human glycosylasparaginase cDNA [Fisher, Tollersrud & Aronson (1990) FEBS Lett. 269, 440-444]. The beta-subunit from all three species has an N-terminal threonine reported to be involved in the reaction mechanism for the human enzyme [Kaartinen, Williams, Tomich, Yates, Hood & Mononen (1991) J. Biol. Chem. 266, 5860-5869]. The native enzyme appeared as a heterodimer among the mammals, whereas the chicken enzyme had a greater molecular mass and is probably either a tetramer or a heterodimer bound to an unrelated peptide(s). All glycosylasparaginases were thermostable, requiring temperatures between 65 degrees C and 80 degrees C to be irreversibly inactivated. In addition, they were unusually stable at high pH and remained active in the presence of SDS except at low pH. The pH maximum was between 5.5 and 6 except for the rat and mouse enzymes which had a broad maximum between pH 7 and 8. A number of other properties were observed which also distinguish the enzyme from individual and closely related species.

scholarly journals Investigation on the Effect of Addition of Fe3+ Ion into the Colloidal AgNPs in PVA Solution and Understanding Its Reaction Mechanism

2017 ◽  
Vol 17 (3) ◽  
pp. 439 ◽  
Author(s):  
Roto Roto ◽  
Marcelina Marcelina ◽  
Nurul Hidayat Aprilita ◽  
Mudasir Mudasir ◽  
Taufik Abdillah Natsir ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Reaction Mechanism ◽  
Polyvinyl Alcohol ◽  
Aqueous Solutions ◽  
Surface Plasmon ◽  
Ag Nanoparticles ◽  
Capping Agents ◽  
Colorimetric Methods

Analysis of Fe3+ ion present in aqueous solutions is always of interests. Recently, this ion has been analyzed by colorimetric methods using colloid of silver nanoparticles (AgNPs) in capping agents of polymers. The reaction mechanism between AgNPs and Fe3+ is still subject to the further investigation. In this work, 1,10-phenanthroline was used to probe the reaction mechanism between AgNPs and Fe3+ ion in the solution. The colloids of AgNPs were prepared in the polyvinyl alcohol (PVA) solution and reacted with Fe3+. The colloid surface plasmon absorbance decreases linearly along with the increase in Fe3+ concentration. The addition of 1,10-phenanthroline to mixture changes the solution to red, indicating that the reaction produces Fe2+. This suggests that the reduction of the AgNPs absorbance is the result of oxidation of the Ag nanoparticles along with the reduction of Fe3+.

Investigation of Cu(II) adsorption from aqueous solutions by NKF-6 zeolite

2011 ◽  
Vol 63 (3) ◽  
pp. 395-402 ◽  
Author(s):  
H. Zhang ◽  
D. Zhao ◽  
L. Chen ◽  
X. J. Yu
Keyword(s):  
Aqueous Solutions ◽  
Outer Sphere ◽  
Low Ph ◽  
Ambient Conditions ◽  
Temperature Dependent ◽  
Ph Values ◽  
Batch Technique ◽  
Negative Effect ◽  
High Level ◽  
Positive Effect

Adsorption of Cu(II) from aqueous solutions using NKF-6 zeolite was investigated by batch technique under ambient conditions. The adsorption was investigated as a function of pH, ionic strength, fulvic acid (FA), foreign ions and temperature. The results indicated that the adsorption of Cu(II) on NKF-6 zeolite gradually increases from 0 to 90% with increasing pH at pH<6.5, and maintains high level at pH>6.5. Outer-sphere complexation or ion exchange may be the main adsorption mechanism of Cu(II) to NKF-6 zeolite at low pH values, whereas the adsorption of Cu(II) at pH>6.5 is mainly dominated by inner-sphere complexation or precipitation. A positive effect of FA on Cu(II) adsorption onto NKF-6 zeolite is observed at low pH values, while a negative effect of FA is observed at high pH values. The thermodynamic parameters (i.e., ΔH0, ΔS0 and ΔG0) for the adsorption of Cu(II) were determined from the temperature dependent isotherms at 20, 40 and 60°C, respectively, and the results indicated that the adsorption reaction is favoured at low temperature. The results suggested that the adsorption process of Cu(II) on NKF-6 zeolite is spontaneous and exothermic.

scholarly journals Using macroporous N-chlorosulfonamide S/DVB copolymer as an aid to iron removal from water

2007 ◽  
Vol 79 (9) ◽  
pp. 1491-1503 ◽  
Author(s):  
Romuald Bogoczek ◽  
Elżbieta Kociołek-Balawejder ◽  
Ewa Stanisławska ◽  
Agnieszka Żabska
Keyword(s):  
Oxidation Reaction ◽  
Cation Exchanger ◽  
Low Ph ◽  
Ferrous Ions ◽  
Acidic Media ◽  
Amberlyst 15 ◽  
Basic Stage ◽  
Poorly Soluble ◽  
Chloramine T ◽  
Ferric Oxides

The de-ironing of water is a basic stage in water-treating technology. Consequently, the oxidation of easily soluble Fe(II) to poorly soluble Fe(III) compounds is indispensible. In order to oxidize Fe(II) ions to Fe(III), a macromolecular and macroporous product in bead form was used: polystyrene cross-linked by divinylbenzene, which contains pendant N-chlorosulfonamide groups in both the sodium and hydrogen forms. To assist the process of removing residual iron from water, this polymer - a macromolecular analog of Chloramine T, containing more than 4.0 mequiv of active chlorine/g - was prepared, starting from the sulfonate cation exchanger Amberlyst 15 by a three-step transformation of its functional groups. The investigations were carried out using both the batchwise and column methods, and 0.0025 M as well as 0.02 M FeSO4 solutions with different acidity were used. We found that the oxidation of ferrous ions to ferric by N-chlorosulfonamide copolymer was effective and was favored by a low pH. The oxidative ability of the copolymer was 225 mg Fe(II)/g. We established that the oxidation reaction could be operated in two directions. In acidic media (pH < 2.5), Fe(III) ions remained in the solution as products of the reaction. The higher the pH, the more the poorly soluble ferric compounds sedimented in the inner structure of the copolymer beads. In this way, new hybrid materials were obtained, i.e., by ferrous/ferric oxides and hydroxides, by nanoparticles, modified materials which can serve as specific reacting sorbents and catalysts.

Reaction mechanism studies on isoquinoline with hydroxyl radical in aqueous solutions

2007 ◽  
Vol 2 (4) ◽  
pp. 354-358
Author(s):  
Dazhang Zhu ◽  
Shilong Wang ◽  
Xiaoyu Sun ◽  
Yaming Ni ◽  
Side Yao
Keyword(s):  
Reaction Mechanism ◽  
Aqueous Solutions ◽  
Hydroxyl Radical
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