Radiation chemistry and photochemistry of oxychlorine ions. Part 3.—Photodecomposition of aqueous solutions of chlorite ions

Abstract

The steady state and flash photolysis of aqueous solutions of chlorite ion has been investigated. The primary photodecomposition reactions are ClO^–₂[graphic omitted]ClO^–+ O (a), ClO^–₂[graphic omitted]ClO^–+ O^–(b), ClO^–₂[graphic omitted](ClO^–₂)^*[graphic omitted]ClO₂+ ClO^–+ O^–(c), with the oxygen atom being formed in the ³P state at 365 nm, and in the ¹D state at 313 nm and 253.7 nm. (ClO^–₂)^* may be a long lived triplet state of chlorite ion. The primary quantum yields obtained at pH 10 are the following: (i) at 365 nm, ϕ_a= 0.23 ± 0.03, ϕ_b=ϕ_c= 0.077 ± 0.003., (ii) at 313 nm, ϕ_a= 0.066 ± 0.002, ϕ_b=ϕ_c= 0.065 ± 0.003, (iii) at 253.7 nm, ϕ_a= 0.11 ± 0.005, ϕ_b=ϕ_c= 0.08 ± 0.003.

A complete mechanism for the photodecomposition is proposed, and the data are consistent with the reaction of O(³P) with ClO^–₂ proceeding by two paths O(³P)+ ClO^–₂→ O₂+ Cl^–+ O(³P)(d), O(³P)+ ClO^–₂→ ClO^–₃(e) with k_d/k_e= 1.50 ± 0.27.