Chain Reduction of CHCl[sub.3] Photocatalyzed by SPEEK/PVA Films Swollen in Air-Saturated HCO[sub.2]Na Solutions

• Published in: Materials 2023-10, Vol.16 (20)
• Main Authors: Dissanayaka, Radini, Islam, Md Safiqul, Mills, G
• Format: Article
• Language: English
• Subjects: Chemical industry; Electric waves; Electromagnetic radiation; Electromagnetic waves; Herbicides; Pesticides industry
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16206629

Thin cross-linked films containing sulfonated poly(ether etherketone), SPEEK, and poly(vinyl alcohol), PVA, served as efficient photocatalysts for the reduction of CHCl[sub.3] when swollen in air-saturated solutions of formate buffers were photolyzed with 350 nm photons. The phototransformation generated CH[sub.2]Cl[sub.2], CO[sub.2] and Cl[sup.−] 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[sup.−]), larger than 1 were obtained in the presence of air. These findings, together with the occurrence of a post-irradiation Cl[sup.−] formation, indicated that the photoreduction took place via a chain process. Reductions photoinitiated by swollen films exhibited ϕ(Cl[sup.−]) values between 3 and 20 times higher than the reactions induced in solutions containing the two polymers. Also, the dependencies of ϕ(Cl[sup.−]) on CHCl[sub.3] or HCO[sub.2] [sup.−] concentration diverged significantly from the trends observed using solutions. Most findings are consistent with the occurrence of a reaction mechanism involving SPEEK radicals, •CO[sub.2] [sup.−] and •CHCl[sub.2] as chain carriers.