Degradation Of Antibiotics In Water By LaNiO₃-derived Composite Activated Peroxymonosulfate

With the rapid development of modern industry and agriculture,the large-scale use of antibiotics leads to the generation of a large amount of antibiotic wastewater,which poses a serious threat to environment and human health.Sulfate radical-based advanced oxidation process（SR-AOPs）is a promising environmental remediation technology to degrade various organic pollutants in water by activating peroxymonosate（PMS）to produce reactive oxygen species（ROS）.Perovskite oxides as the novel functional material can also be applied as catalysts for SR-AOPs due to their high design flexibility,controllable defects to produce ionic or electronic conductivities,controllable surface properties,and stability.However,perovskite materials’limited catalytic performance,easy agglomeration of particles,and metal leaching have become the main bottlenecks limiting its practical application.In this study,modify La Ni O₃by element doping or compound to improve its catalytic performance,and its application in the degradation of antibiotic wastewater was studied.The morphology,structure and catalytic performance of La Ni O₃-derived composites were evaluated by various characterization tests.Finally,the mechanism and pathway of antibiotic degradation by activated PMS were systematically analyzed.The main research contents are as follows:（1）Preparation and properties of La Ni_0.6Co_0.4O₃/Zn O compositesIn this work,La Ni_0.6Co_0.4O₃nanoparticles were evenly and firmly dispersed on Zn O support by the citrate sol-gel method(La Ni_0.6Co_0.4O₃/Zn O)for activating Ofloxacin（OFX）in PMS water.The catalytic rate of the La Ni_0.6Co_0.4O₃/Zn O system was significantly higher than that of single system.The reaction rate constant（k）of La Ni_0.6Co_0.4O₃/Zn O(0.57 min^-1)was 7.125 times that of La Ni O₃(0.08 min^-1)and 57times that of Zn O(0.01 min^-1),respectively.In addition,compared with pure La Ni_0.6Co_0.4O₃,La Ni_0.6Co_0.4O₃/Zn O significantly inhibited metal ion leaching.After 5cycles,the physical and chemical properties of La Ni_0.6Co_0.4O₃/Zn O remained stable,and the degradation efficiency of OFX was still up to 93%.According to reactive oxygen quenching experiment and electron paramagnetic resonance test（EPR）,SO₄^·-,^·OH,^·O₂^-and ¹O₂were the main reactive oxygen species.The degradation intermediates of ofloxacin were tested,and the possible degradation pathway of the La Ni_0.6Co_0.4O₃/Zn O/PMS system was proposed.（2）Preparation and properties of La₂Ni O₄/Co C compositesIn this work,ZIF-67 was first grown in situ on La Ni O₃to form La Ni O₃/ZIF-67and then calcined at high temperature to form La₂Ni O₄/Co C.Its morphology,physicochemical properties and structure were analyzed by characterization tests.OFX was used as the target pollutant,and La₂Ni O₄/Co C was used to activate PMS for its degradation.It was found that the system could rapidly degrade 91.4%OFX within3 minutes,while inhibiting the leaching of Ni and Co.In addition,it was confirmed that the oxygen vacancy promoted the catalytic reaction.A possible degradation pathway of the La₂Ni O₄/Co C/PMS system was proposed through the degradation of intermediates,and the biotoxicity of intermediates was evaluated.The toxicity of OFX degradation process in the catalytic system was expected to increase initially and then decrease until the formation of low-toxicity products.