Effect of thallous ions on the yields of hydrogen and hydrogen peroxide in radiolyzed aqueous solutions

Abstract

The radiolysis of Tl₂SO₄ in neutral and in 0.8 N H₂SO₄ aqueous solutions in the presence and absence of air was investigated. In the absence of air and with low doses of radiation, a steady-state concentration of H₂O₂ is observed. In air-saturated solution G(H₂O₂) decreases with Tl⁺ concentration. The effect of Tl⁺ on G_H2O2 was measured by two independent methods, following G(H₂O₂) in aerated solutions and by measuring G(H₂O₂^{18, 18}) formed in H₂O¹⁸ in the presence of H₂O₂^{16, 16} as protective additive. In neutral and acid solutions, G(H₂)=G_H2= 0.42±0.02, which was independent of Tl⁺ concentration. The relatively high efficiency of Tl⁺ for scavenging the precursor of H₂O₂ is discussed and compared with that of other reactants known to diminish G_H2O2. The mode of formation of the “molecular” products in the radiolysis of water is discussed in the light of the findings.