Simultaneous H2 production and pollutant removal from biodiesel wastewater by photocatalytic oxidation with different crystal structure TiO2 photocatalysts

Abstract

This work was performed to test the feasibility of hydrogen (H2) production simultaneously with pollutant removal from biodiesel wastewater by the photocatalytic oxidation via different crystal structure TiO2 photocatalysts at ambient temperature (∼ 30 °C) and pressure. It was found that the simultaneous H2 production and pollutant removal could not be achieved using a fresh biodiesel wastewater, but proceeded well when the wastewater was diluted around 3.3-fold. The crystal structure of TiO2 markedly affected the rate of H2 production and pollutant removal. The mixed anatase–rutile phase crystal structure TiO2 photocatalysts exhibited a higher photocatalytic activity than that in the single rutile crystal structure, probably due to the co-presence of rutile and anatase phases of TiO2. The properties of the mixed crystal structure TiO2 photocatalyst, including the crystallite size, BET surface area, pore volume, band gap energy and point of zero charge (PZC) value affected the photocatalytic activity more than the phase composition. Among the evaluated mixed crystal structure, the TiO2 photocatalyst treated at 400 °C (T400) showed a great potential to produce H2 simultaneously with pollutant removal of approximately 19.83%, 83.13% and 84.13% of COD, BOD and oil & grease, respectively, with a H2 production rate of 67.4 µmol/h.