LaCoO3/La-doped g-C3N4 heterojunctions for synergistically promoted photocatalytic degradation of enrofloxacin in an immobilized photocatalyst- polymer film-based airlift photocatalytic reactor

Developing highly active photocatalysts with low recombination rates of photo-promoted charge carriers has been widely studied and become an emerging research area. Herein, we report on constructing a Z-scheme LaCoO₃/La-doped g-C₃N₄ heterojunction photocatalyst and immobilizing it by a polyaniline film. A single split-plate airlift photocatalytic reactor including the polyaniline-immobilized LaCoO₃/La-doped g-C₃N₄ photocatalyst film was built and used for the photodegradation of enrofloxacin and real pharmaceutical wastewater. The operation of the designed photocatalytic reactor using the immobilized photocatalyst hybrid film presented 97.2 % degradation efficiency within 60 min (and 81.0 % TOC reduction), compared to 90.4 % in the slurry system. Besides, 91 % chemical-oxygen-demand (COD) and 83.5 % total-organic-carbon (TOC) have been removed from the real pharmaceutical wastewater effluent within 90 min. The immobilized LaCoO₃/La-doped g-C₃N₄ photocatalyst was effectively recycled five times. The reaction mechanism was analyzed in details, and the ^•O₂^- and ^•OH radicals were the main reaction species. The band structure investigation showed that the Z-system heterojunction was built efficiently.