Photocatalytic oxidation of 1,3-dichloro-2-propanol aqueous solutions with modified TiO2 catalysts

The photochemical and photocatalytic oxidation of 1,3-dichloro-2-propanol (1,3-DCP, 0.024 M) was performed in a batch reactor, at room temperature, using UV radiation (254 nm), H2O2 (0.081 M and 0.163 M) as oxidant, and TiO2-based catalysts modified with platinum, cerium and iron (65 mg/L catalyst load). The profile of the oxidation of 1,3-DCP was followed by monitoring the target compound degradation, the total organic carbon removal and the chloride ion production and it was deduced that the addition of the catalysts enhances the mineralization process taking place during the oxidation with simultaneous 1,3-DCP conversion. Based on the oxidation intermediates detected a reaction pathway for the degradation of 1,3-DCP is proposed. Also, a seven-step reaction mechanism was proposed, according to which a total chlorinated intermediate was produced, that degraded further to chloroacetic, acetic and formic acids, while chloroacetic and acetic acids were mineralized with simultaneous production of formic acid. Finally, based on the proposed mechanism a kinetic analysis was conducted in order to calculate the respective rate constants and it was deduced that with the catalyst's addition, the direct mineralization of the chlorinated intermediate was enhanced increasing TOC removal, whereas formic acid was resistant to further degradation, posing an obstacle to the total mineralization of 1,3-DCP.