Find in Library

Thin cross-linked films containing sulfonated poly(ether etherketone), SPEEK, and poly(vinyl alcohol), PVA, served as efficient photocatalysts for the reduction of CHCl₃ when swollen in air-saturated solutions of formate buffers were photolyzed with 350 nm photons. The phototransformation generated CH₂Cl₂, CO₂ and Cl⁻ as products. The utilization of the continuous extraction method coupled with in situ potentiometry enabled kinetic determinations of the reaction progress. Quantum yields of halide ion formation, ϕ(Cl⁻), larger than 1 were obtained in the presence of air. These findings, together with the occurrence of a post-irradiation Cl⁻ formation, indicated that the photoreduction took place via a chain process. Reductions photoinitiated by swollen films exhibited ϕ(Cl⁻) values between 3 and 20 times higher than the reactions induced in solutions containing the two polymers. Also, the dependencies of ϕ(Cl⁻) on CHCl₃ or HCO₂⁻ concentration diverged significantly from the trends observed using solutions. Most findings are consistent with the occurrence of a reaction mechanism involving SPEEK radicals, •CO₂⁻ and •CHCl₂ as chain carriers.