The oxidation of aqueous bromide ions by hydroxyl radicals. A pulse radiolytic investigation

Oxidation of Br^- by OH radicals in neutral and acid aqueous solutions has been investigated. The reaction mechanism involves the following reactions and rate constants: OH + Br^- → BrOH^-, k = (1.06 ± 0.08) × 10¹⁰ M^-1 sec^-1; BrOH^-→ Br^- + OH, k = (3.3 ± 0.4) × 10⁷ sec^-1; BrOH^- → Br + OH^-, k = (4.2 ± 0.6) × 10⁶ sec^-1; BrOH^- + H⁺→ H₂O + Br, k = (4.4 ± 0.8) × 10¹⁰ M^-1 sec^-1; BrOH^- + Br^- → OH^- + Br₂^-, k= (1.9 ± 0.3) × 10⁸ M^-1 sec^-1; Br + Br^- → Br₂^-, k ≃ 10¹⁰ M^-1 sec^-1 (previous work). A new absorption peak of Br₂^- at 700 nm is reported. A new equilibrium reaction of Br₂^- with Br^- to produce Br₃^2- is proposed.