Synthesis of ZnFe₂O₄ nanoparticles for photocatalytic removal of toluene from gas phase in the annular reactor

Spinel type mesoporous ZnFe₂O₄ nanoparticles were synthesized by sol-gel auto combustion method and characterized by XRD, FE-SEM, DRS and BET. XRD pattern of prepared nanocrystals showed that ZnFe₂O₄ spinel formed in cubic structure and the mean crystallite size was 25 nm. FE-SEM image showed that prepared particles were in nanoscale with low aggregation and porous structure. From DRS results, the optical band gap was calculated about 1.87 eV. From BET analysis, specific surface area of prepared nanoparticles was obtained 39 m²/g. The prepared nanoparticles application was studied on the removal of toluene from gas phase by photocatalytic process under UV and visible irradiation in the annular photoreactor. The prepared nanoparticles were capable to remove about 60% of toluene with 900 ppmv concentration. The prepared nanoparticles had more efficiency than commercial ZnO and TiO₂ nanoparticles in the photocatalytic removal of toluene. The operational parameters such as initial concentration of pollutant, catalyst loading, photoreactor humidity and light intensity were studied.