Abstract
UV-irradiated titanium oxide can degrade various kinds of organic compounds by hydroxyl radicals (HO·) that are produced during the reaction. We recently found that in this reaction, H2O2 is formed at a concentration level of ppm (parts per million) from water and the initial rate of formation of H2O2 is proportional to the initial rates of degradation of HCOOH and HCHO. On the other hand, Fenton reaction also utilizes HO· to degrade organic compounds. In this reaction, however, H2O2 must be added to a reaction mixture to produce HO·. To overcome this disadvantage, this work investigates a new process consisting of the photocatalytic reaction on UV-irradiated titanium oxide and the Fenton reaction on a Nafion membrane adsorbing ferrous ions, in which the Fenton reaction proceeds by utilizing the H2O2 formed in the photocatalytic reaction. The experimental result using HCOOH as a reactant clearly showed that the Fenton reaction occurs without addition of H2O2 and adjustment of a pH value and the combined process results in an increase in the rate of degradation of HCOOH. Also, it was confirmed that the Nafion membrane after repeated seven batch runs can quickly be regenerated with L(+)-ascorbic acid and then used repeatedly.
