Mechanistic insight into SO4•-/•OH radical for enhancing stability and activity of LaMO3 perovskite toward detoxification of bulk pharmaceutical wastewater: Stoichiometric efficiency and controlled leaching study

This study aims to investigate the detoxification of real pharmaceutical manufacturing wastewater by PMS activated with perovskite LaMO3 (M = Cu, Co, Fe), synthesized by citric sol-gel method. The textural properties of synthesized perovskite were monitored by BET, FESEM/EDS, TEM, XRD, FTIR, and XPS techniques. The effects of key parameters (PMS dose, catalyst, pH and reaction temperature) on ofloxacin degradation along with PMS utilization efficiency as well as PMS consumption were evaluated in detail. Catalyst LaCoO3 exhibited the excellent catalytic activity and stability towards the degradation of ofloxacin (97.11 %) and COD (79.41 %) at optimum operating conditions. Removal of ofloxacin and COD were suppressed by 7 % and 9 % over the fourth cycle, along with minor leaching of Co were observed. Quenching experiments and EPR results demonstrated that both ROS species (SO4 center dot- and (OH)-O-center dot) were dominant species for ofloxacin degradation in LaCoO3/PMS system. The treatment cost for ofloxacin degradation in LaCoO3/PMS system was estimated to be 40.78$/m(3) of real pharmaceutical wastewater. Six plausible degradation pathways of ofloxacin were proposed based on intermediate compounds identified by GC-MS and reported literature.

Automated summary

This study used LaMO3 (M = Cu, Co, Fe) perovskite activated PMS to investigate the detoxification of real pharmaceutical manufacturing wastewater. The synthesized perovskite was characterized by various techniques. The optimal conditions for the degradation of ofloxacin and COD were achieved with LaCoO3 as the catalyst. The dominant reactive oxygen species for ofloxacin degradation in the LaCoO3/PMS system were identified as SO4 center dot- and (OH)-O-center dot.