B. G. Ershov

Reduction of Ag+ on Polyacrylate Chains in Aqueous Solution

Silver ions are reduced in aqueous solutions that contain sodium polyacrylate or partly carboxylated polyacrylamide or glutaric acid. The reducing agent is the hydrated electron (generated γ-radiolytically) or hydrogen. Complexes of small silver clusters with the polyelectrolyte are formed in the early stages of reduction, the color of the solutions varying from rose to green or blue depending on the size of the complexed silver clusters. In the case of 10% carboxylated polyacrylamide, large colored complexes are not formed, which indicates that a high carboxylate density along the polymer chain is necessary for their formation. The complexes are stable toward heat (100 °C) and oxygen. In the later stages of reduction, the long-wavelength absorptions of the silver−polyacrylate complexes disappear. The UV absorption bands of a magic cluster (probably Ag9+) are present during a short time interval, until the plasmon absorption band of metallic nanoparticles develops at 380 nm. The colored clusters react wit...

Solubility of oxygen and nitrous oxide in aqueous solutions of NaCl: a pulse radiolysis study

Abstract The saturation concentrations of O 2 and N 2 O in aqueous solution were measured for different amounts of NaCl by observing the decay of the absorption of hydrated electrons, which were generated during the radiolysis of water. The results are in good agreement with an empirical model based on numerous static measurements of the “salting-out” effect.

A pulse radiolysis study of the oxidation of Br− by Cl2˙− in aqueous solution: formation and properties of ClBr˙−

The oxidation of Br− by Cl2˙− is investigated by pulse radiolysis in aqueous solutions of NaCl and NaBr. Depending on the ratio of the concentration of Br− to Cl−, the main product being observed is either Cl2˙−, ClBr˙− or Br2˙−. The mixed radical anion ClBr˙− exhibits a broad absorption band at 350 nm with e350 = 9300 dm3 mol−1 cm−1. The rate constants of the equilibrium Cl2˙− + Br− ⇌ ClBr˙− + Cl− are determined to be kf = 4 × 109 and kb = 1.1 × 102 dm3 mol−1 s−1.

Colloidal copper in aqueous solutions: radiation-chemical reduction, mechanism of formation, and properties

Colloidal copper has been obtained by γ-irradiation of aqueous solutions of copper (II) perchlorate in the presence of alcohol and polyethyleneimine (PEI). The sols are spherical particles about 4 nm in diameter, which are quickly oxidized by oxygen or other oxidants. When CuII is not entirely incorporated into the complex with PEI, disproportionation of CuI aqua complexes formed affords the metal, along with Cu2O. Reduction of the PEI complex of CuI by hydrated electrons gives only colloidal copper. The copper ions can be reduced on the surface of silver sols. Optical parameters of the resulting bimetallic particles have been studied. The presence of copper ions leads to broadening of the absorption band associated with the silver sols and shifts it to the UV region, which is due to the transfer of electrons from copper to silver. Three copper monolayers are enough to cause plasmon absorption of colloidal copper.

Decomposition of ozone in water at pH 4–8

A systematic study of the ozone decomposition in water in the pH range 4–8 was carried out.

Pulse radiolysis studies of the reactions of eaq− and ·OH with ClO3− ions in aqueous solution

The rate constants of the reactions of eaq− and ·OH with ClO3− in aqueous solutions are determined by pulse radiolysis studies. The hydrated electron reacts with ClO3− with a rate constant of 1.6 × 105 M−1 s−1 to yield the ClO32− radical anion. Its optical absorption exhibits two bands at 245 nm (e=900 M−1 cm−1) and at 500 nm (e=500 M−1 cm−1). The reaction of the ·OH radical with ClO3− is too slow to measure a rate constant; an upper limit is estimated to be <1 × 105 M−1 s−1. The rate constants for the reactions of the ClO32− radical anion with the ·OH radical and the ·O− radical ion are determined to be 1 × 1010 and 1.2 × 109 M−1 s−1, respectively.

Short-lived metal clusters in aqueous solutions: formation, identification, and properties

The formation and properties of short-lived homo- and heteronuclear metal clusters in aqueous solutions were investigated by pulse radiolysis. These species arise in early stages of the aggregation of metal atoms and ions in unusual oxidation states. The conditions favoring the formation of positively charged “magic” clusters and intermediate heterometallic clusters were elucidated.

Early stages of metal clusters in aqueous solution: Reaction of Zn+ and Cd+ with Ag+

Abstract Zn + and Cd + are pulse radiolytically generated in solutions which also contain low concentrations of silver ions. Both of these monovalent ions react rapidly with the silver ion yielding a free silver atom (Ag 0 ) through electron transfer, or a mixed metal cluster [(CdAg) 2+ ], respectively. The free silver atom and the cluster subsequently react with excess silver ions producing dimer (Ag 2 + ) and trimer (Ag 3 2+ ) silver ions, which are also observed in a solution containing only silver ions.

Sorption of Tc(VII) and Am(III) by carbon materials: effect of oxidation

In this work we studied the effect of oxidation on the sorption properties of carbon materials, produced on the basic of activated carbons FAS and VSK in relation to radionuclides Am(III) and Tc(VII). It has been found that the oxidation increases the distribution coefficients for the extraction of radionuclides of sorption nitric acid raising agents. As to identify the mechanism of the oxidation influence on the sorption properties the physical and chemical properties of the synthesized samples (porous surface structure, IR-spectrums etc.) were studied. The possibility of removal of radionuclides from the real industrial solutions of complex composition using of the obtained carbon nanomaterials was investigated.

Metal Nanoparticles with PW11O397- and P2W17O6110- Heteropoly Anions as Stabilizing Agents: Radiation-Chemical Preparation and Properties

The radiation-chemical reduction of silver, copper, cadmium, thallium, lead, cobalt, and nickel ions to form stable metal nanoparticles was studied in the presence of PW11O397- and P2W17O6110- heteropoly anions in aqueous solutions containing sodium formate or isopropanol. The heteropoly anions were found to be efficient stabilizing agents for the resulting sols. The optical characteristics of the sols were determined.