Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9876329 | Radiation Physics and Chemistry | 2005 | 13 Pages |
Abstract
Reduction of Cu2+ ions with and without Iâ as a ligand was studied in N2-purged alcoholic solutions by pulse radiolysis. In the absence of iodide ion, the initial rate constant for eâsol reaction with Cu2+ was determined following the decay of solvated electrons in different alcohols; kbimol values are in the range of 0.8-1.1Ã1010 dm3 molâ1 sâ1. In the presence of 10â3 mol dmâ3 KI, the respective kbimol remained almost same. Generally, on reduction, Cu(II) ion changes to Cu(I) ion initially and later it produces metallic copper (Cu°), and the stability of these intermediates depends on the conditions of the matrix. In the presence of Iâ, Copper ions such as Cu(II) or Cu(I) ions get reduced to metallic copper (Cu°) having initial absorption around 740 and below 400 nm. Later, at 100 μs time after the electron pulse, it gets transformed into a nanoparticle with an absorption band at 580 nm. Such formation of copper nanoparticle was observed only in 2-propanolic medium in the presence of iodide ions. During γ-radiolysis of N2-purged 1.5Ã10â4 CuSO4 solutions in 2-propanol, reddish pink colored copper nanoparticles were formed, which are quite similar to those reported earlier in aqueous solution. But, in the presence of Iâ (2-propanolic solutions), such phenomenon was not noticed on γ-radiolysis. Interestingly, the formation of copper nanoparticle was observed also in the reactions of copper (II) ions with alcohol radicals formed during γ-radiolysis in N2O-purged system, where eâsol were scavenged by N2O. The nanoparticles generated both in N2 and N2O-purged alcoholic systems, viz. methanol, ethanol and 2-propanol, were found to be oxygen sensitive. The contradictory results from pulse and γ-radiolysis studies in the presence and absence of iodide ions are explained to account for the nanoparticle generation.
Keywords
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Physical Sciences and Engineering
Physics and Astronomy
Radiation
Authors
G.R. Dey,