Photoreduction of CCl3F in aqueous solutions containing sulfonated poly(ether etherketone) and formate buffers

Chain Reduction of CHCl3 Photocatalyzed by SPEEK/PVA Films Swollen in Air-Saturated HCO2Na Solutions

“…The earlier experiments verified that a fast equilibration was established between fluid phase and films when the latter were immersed in vigorously stirred solutions. Preliminary tests using ion chromatography (IC) confirmed that Cl − ions photogenerated inside films experienced constant extraction into the aqueous phase, where they were quantified using an ion-selective electrode (ISE), as reported previously [10][11][12].…”

“…Furthermore, the CHCl 3 photoreduction under air was only 30% less efficient than in the presence of Ar, and proceeded via a different mechanism. In contrast, the photoreduction of CCl 3 F showed a higher efficiency with air than without, but no chain reduction occurred [12]. Such findings were unexpected because O 2 inhibits transformations involving reducing radicals.…”

“…In the polymer system, SPEEK acts as the sensitizer, whereas PVA serves as the H-atom donor. The illumination of SPEEK/PVA blends yields α-hydroxy radicals of the polyketone, HSPEEK•, a strong reducing agent able to dehalogenate several chloromethanes such as CCl 4 , CHCl 3 and CCl 3 F [10][11][12]. Since both SPEEK and PVA are soluble in H 2 O, the preparation of cross-linked thin polymer films (insoluble in water) is feasible via solution casting.…”

“…Thus, photoreductions initiated by SPEEK/PVA blends can be studied in water and also using films which are either dry or swollen in aqueous solutions. Recent investigations showed that CCl 4 and CHCl 3 undergo efficient chain photoreductions upon the photolysis of air-free solutions of SPEEK/PVA blends in the presence of formate buffers containing HCO 2 H and HCO 2 − [11,12]. CCl 4 is a toxic pollutant that has been found to be a significant contributor to underground solvent plumes called dense nonaqueous phase liquid (DNAPL) [13].…”

“…Consequently, the present report is based on results from experiments that employed SPEEK derived from this precursor. Also, high concentrations of the H-atom donor and excess chloromethanes were previously identified as conditions yielding the highest efficiencies [10][11][12]. Thus, irradiations were conducted under these conditions and using thin, cross-linked SPEEK/PVA films swollen in solutions of formate buffers saturated with air.…”