Effect of Al₂O₃ Nanoparticles on Radiolytic H₂O₂ Production in Water

The yields of H 2 O 2 have been determined in aqueous slurries in the pH range of 1−13 with various amounts of added Al 2 O 3 nanoparticles. The addition of Al 2 O 3 generally decreases H 2 O 2 yields at all pH values within this range in the gamma radiolysis of both deaerated and aerated slurries, except at pH above 11. Very little effect of pH is observed in the gamma radiolysis of deaerated systems in the pH range of 3−8, whereas a large increase in H 2 O 2 yields is observed in aerated Al 2 O 3 slurries as the pH increases or decreases from neutral. Results with 5 MeV H and He ions for H 2 O 2 yields in aerated Al 2 O 3 slurries above pH 4 have similar trends as in gamma radiolysis, except with different absolute yields. Scavenger capacity studies using methanol as an OH • radical scavenger show that the decrease in H 2 O 2 yields with added Al 2 O 3 occurs at relatively long time scales and is probably due to reaction of the solid nanoparticles with OH • radicals.