Degradation Of Typical Antibiotic Pollutants In Water By Persulfate Activated With Magnetic Loofah Biochar:Performance And Mechanism

The environment is the people’s livelihood,the green mountains are beautiful,the blue sky is happy,and the water source is life.With the concept of"green water and green mountains are golden mountains and silver mountains"deeply rooted in the hearts of the people,environmental protection has attracted more and more attention,and environmental governance has also achieved a series of remarkable results.However,in recent years,the emergence of new pollutants in the water environment has attracted extensive attention,such as endocrine disruptors,antibiotics,micro plastics,etc.The corresponding research,institutional system and treatment technology are still in the stage of exploration and development.China is a large country in the production and use of antibiotics.However,due to the imperfection of the relevant standard system for the emission of antibiotic pollutants,the establishment of a complete monitoring system and restriction standards,and the effective control of the emission,antibiotic pollution has become a more serious pollution phenomenon.The purification technology of antibiotics has attracted extensive attention.The sulfate radical（SO₄·^-）based advanced oxidation processes（AOPs）exhibited significant potential in the treatment of antibiotics.In this study,the magnetic biochar（Fe₂O₃@LBC）derived from loofah was prepared to activate persulfate（PS）for cephalexin（CEX）degradation.Under the optimal conditions,73.9%of CEX was removed in the Fe₂O₃@LBC/PS system.Free radicals quenching experiments and electron paramagnetic resonance（EPR）analysis revealed that HO·and SO₄·^-were responsible for the degradation of CEX.The C-OH of the catalyst played a crucial role in the degradation process.In addition,the conversion between Fe³⁺and Fe²⁺enhanced the degradation of CEX by producing SO₄·^-.The degradation performance of other antibiotics and CEX in different water matrices indicated the broad adaptability and applications of Fe₂O₃@LBC.The main intermediates and the possible transformation pathways were proposed.On the basis of the previous experiment,in order to improve the economic applicability of biochar catalysts,we attempted to apply a deactivated magnetic loofah biochar with adsorbed Cu²⁺directly as a peroxymonosulfate（PMS）activator to remove tetracycline（TC）.The catalyst showed high activity in the process of activating PMS to degrade TC,and the removal of TC could reach 97.6%.Cu-Fe@LBC also had good repeatability,and the removal of TC could still reach more than 80%after 5 cycles.In addition,the adsorption sites of copper ions were determined by XPS analysis,which existed on the catalyst surface in the form of COO-Cu.Free radicals quenching experiments and electron paramagnetic resonance（EPR）analysis revealed that HO·and ~1O2 were responsible for the degradation of TC.The possible degradation pathway and mechanism were proposed.In a wide p H range and with different coexisting anions,the removal of TC by the catalytic system could reach more than 80%.Therefore,this work provides not only an insight into the PMS activation by reusing waste biochar catalysts but also provides an idea of treating waste with waste to use transition metal elements.