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, ϕa= 0.23 ± 0.03, ϕb=ϕc= 0.077 ± 0.003., (ii) at 313 nm, ϕa= 0.066 ± 0.002, ϕb=ϕc= 0.065 ± 0.003, (iii) at 253.7 nm, ϕa= 0.11 ± 0.005, ϕb=ϕc= 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 kd/ke= 1.50 ± 0.27.