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

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 GH2O2 was measured by two independent methods, following G(H2O2) in aerated solutions and by measuring G(H2O218, 18) formed in H2O18 in the presence of H2O216, 16 as protective additive. In neutral and acid solutions, G(H2)=GH2= 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 GH2O2. The mode of formation of the “molecular” products in the radiolysis of water is discussed in the light of the findings.