In situ H2O2 generation for de-emulsification of fine stable bilge water emulsions

Herein, the design and construction of a photo-electrochemical system for in situ generation of hydrogen peroxide (H2O2) and de-emulsification of fine stable bilge water emulsions is described. By coupling visible-light driven photocatalytic oxidation at Pt/TiO2 photo-anode and electro-Fenton oxidation at Fe2O3 loaded graphite cathode in an undivided cell, it was found that the generated H2O2 species, and the subsequently formed hydroxyl radical (% OH) can be employed to readily de-emulsify stable bilge water emulsions. The demonstrated high efficiency of this design is potentially due to the synergetic effect between the efficient separation of photoproduced electron-hole pairs in the Pt/TiO2 photo-anode and the transfer of electrons to the Fe2O3 loaded graphite cathode to create more H2O2 and % OH radicals. The concentration of generated H2O2 in solution over the duration of the photo-electrochemical experiments was determined to be 106.21 mg L-1 within 240 min. The formation of % OH radicals during photo-electrochemical treatment was confirmed and measured by the photoluminescence method using coumarin as a chemical trap for % OH radicals. Reusability studies showed there was no significant difference in chemical oxygen demand removal efficiency and the generation of H2O2 after ten sequential experimental runs, implying the catalytic activity of the system can be maintained for long periods.