Photoreduction of CHCl3 in Aqueous SPEEK/HCO2- Solutions Involving Free Radicals

The Journal of Physical Chemistry. a
M S IslamG Mills

Abstract

Exposure of sulfonated poly(ether etherketone), SPEEK, in aqueous solutions to 350 nm photons induced reduction of CHCl3 to CH2Cl2 and chloride ions in the presence of HCO2H/HCO2- buffers or poly(vinyl alcohol), PVA. The kinetics of the SPEEK-sensitized photoreaction was characterized by quantum yields of halide ion formation, ϕ(Cl-), evaluated from in situ determinations of [Cl-]. Particularly efficient reductions took place when formate buffers served as H atom donors in the absence of air and with excess CHCl3. The dependence of ϕ(Cl-) on the inverse square root of the light intensity together with postirradiation formation of Cl- in the dark indicated that the CHCl3 photoreduction occurred via a chain process. EPR determinations identified the α-hydroxy radical of SPEEK and •CHCl2 as chain carriers. Most of the kinetic findings were rationalized in terms of a free radical mechanism where dimerizations of the radicals acted as termination steps. Photoreduction of CHCl3 was also detected in the presence of air albeit with lower quantum efficiencies. Observations made during postirradiation experiments indicated that a chain process was also operative under such conditions.

References

May 25, 2002·Environmental Science & Technology·Paul J SquillaceDana W Kolpin
Dec 28, 2005·Langmuir : the ACS Journal of Surfaces and Colloids·A S KorchevG Mills
Oct 25, 2007·The Journal of Physical Chemistry. a·Roman FlyuntKlaus-Dieter Asmus
Oct 16, 2009·Journal of Hazardous Materials·Jing LiNansheng Deng
Oct 12, 2012·Photochemistry and Photobiology·Alissa M ChanPatrick E Hoggard
May 10, 2013·The Journal of Physical Chemistry. a·Brian K LittleG Mills
May 28, 2016·The Journal of Physical Chemistry. a·PaviElle LockhartG Mills
May 11, 2017·The Journal of Physical Chemistry. a·J R BlackG Mills

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