Ultrasound-induced PMS activation for acrylonitrile degradation with series LTZ perovskite-like catalysts: Synergistic and mechanistic insight

The degradation of toxic and refractory pollutants requires an efficient, environmentally friendly, and cost-effective treatment process to address the current challenges associated with wastewater. Herein, we present a hybrid system (LaTixZn1-xO3/PMS/US) that utilizes ultrasound irradiation to activate PMS (peroxymonosulfate) for the degradation of acrylonitrile. The system incorporates a series of perovskite-like catalysts LaTixZn1-xO3 (x = 0.2, 0.4, 0.6, 0.8, 1) fabricated using citric sol-gel method. The texture properties, surface morphology and composition of synthesized catalysts were analyzed by TEM, FESEM/EDS, FTIR, XRD and XPS. Furthermore, influences of operation parameters such as catalyst dose, PMS dose, pH, and US power, co-existing anions were investigated along with PMS utilization efficacy and its consumption rate. Under the optimal conditions, catalyst 0.75LTZ exhibited remarkable catalytic activity for acrylonitrile degradation (98.7%), with synergistic index value (3.363). The trapping experiments and EPR analysis revealed that ROS (SO4 center dot- and (OH)-O-center dot) both played a pivotal role in acrylonitrile removal, accordingly a rational mechanism was elucidated. The co-existing ions species HCO3- showed a strong inhibitory effect on acrylonitrile degradation compared to other ionic species (NO3-, Cl-, and SO42-). Based on the GC-MS analysis and existing literature, four possible pathways for the degradation of acrylonitrile were suggested. The treatment process incurred a cost of around 0.081$ per liter of wastewater in the 0.75LTZ/PMS/US system.