Study On The Performance And Mechanism Of Metal-based Biochar Materials Activated Peroxymonosulfate For Organic Pollutant Degradatio

In the past few decades,due to the rapid development of industrialization,urbanization,and commercialization,increasing numbers of organic pollutants have been discharged into the aquatic environment.These emerging contaminants posed a huge threat to human health and ecosystems,especially toxic,persistent,and biodegradable organic compounds such as endocrine disrupting chemicals（EDCs）,pharmaceutical and personal care products（PPCPs）,dyes,and other persistent organic pollutants,which were difficult to remove by traditional methods.Advanced oxidation processes（AOPs）,as an effective method for the efficient removal of refractory organic pollutants in wastewater,shows an excellent prospect in the field of organic pollutant treatment due to their high reactivity and high oxidation capacity.Among them,sulfate radical-based advanced oxidation processes（SR-AOPs）was able to oxidize organic pollutants and convert them into harmless carbon dioxide and water due to the generation of sulfate radical(SO₄^·-)with high redox potential.The sulfate radical has the advantages of high efficiency and thoroughness,green environmental protection,easy operation,and mild reaction conditions,which makes SR-AOPs a technology and direction with good development prospects.Additionally,persulfate generally includes peroxymonosulfate（PMS）and peroxydisulfate（PDS）.Compared with the symmetric structure of PS,the asymmetric structure of PMS is more easily activated by various activation technologies to produce SO₄^·-with high oxidation activity.Therefore,catalytic activation of PMS has been widely studied in environmental remediation and wastewater treatment.Biochar（BC）is a carbon-rich material that can be obtained from the pyrolysis of agricultural solid waste,which has the advantages of low cost,large specific surface area,strong adsorption capacity,and rich oxygen-containing functional groups.However,the problems of low activity and the difficult separation of pure biochar limit its practical application.Therefore,new biochar composites can be prepared by modifying or loading nanoparticles on biochar.Biochar contributes to the dispersion and stability of nanoparticles,can increase the number of surface active sites,and even produce synergistic effects,thereby improving the physical and chemical properties of the composites.Therefore,biochar composites have been widely used as heterogeneous catalysts for activating PMS in wastewater treatment.In this paper,porous biochar（BC）was prepared from waste mulberry branches to achieve resource reuse,and then transition metal spinel nanoparticles were compounded with BC as the substrate.Two novel magnetic high-efficiency metal-based composite biochar materials were successfully prepared by improved sol-gel combustion reaction and used to activate PMS to efficiently remove various organic pollutants in wastewater.The main research contents are as follows:1.A magnetic copper ferrite and biochar composite（Cu Fe₂O₄@BC）catalyst was prepared by an improved sol-gel calcination method and initially used for the removal of antibiotics ciprofloxacin（CIP）by activated peroxymonosulfate（PMS）.Using Cu Fe₂O₄@BC as the activator,97.8%CIP removal efficiency could be achieved in 30min.After a continuous degradation cycle,the Cu Fe₂O₄@BC catalyst still exhibited great stability and repeatability and could also be quickly recovered by an external magnetic field.Meanwhile,the Cu Fe₂O₄@BC/PMS system presented good stability for metal ion leaching,which was far less than the leaching of metal ions in the Cu Fe₂O₄/PMS system.Moreover,the effects of various influencing factors,such as initial solution p H,activator loading,PMS dosage,reaction temperature,humic acid（HA）,and the inorganic anions were explored.The quenching experiments and the electron paramagnetic resonance（EPR）analysis manifested that hydroxyl radical（·OH）,sulfate radical(SO₄^·-),superoxide radical(O₂^·-),and singlet oxygen（¹O₂）were generated in the Cu Fe₂O₄@BC/PMS system,while ¹O₂ and O₂^·-are mainly involved in the degradation process.The synergistic effect between Cu Fe₂O₄ and BC enhanced the structural stability and electrical conductivity of the material,which promoted the bonding between the catalyst and PMS,resulting in the enhanced catalytic activity of Cu Fe₂O₄@BC.This indicates that Cu Fe₂O₄@BC activating PMS is a promising remediation technique for CIP-contaminated water.2.Cobalt ions with high catalytic activity have limited their application in the field of catalysis due to their high toxicity and easy leaching.The composite materials synthesized in combination with the first stage have the better catalytic ability and stable structure.Based on this,we tried to combine Cu Co₂O₄ with biochar,and successfully synthesized Cu Co₂O₄@BC composite material,and the catalyst was used to activate PMS to degrade 97.3%typical dye rhodamine B within 5 min,achieving a faster and more effective degradation effect.The metal leaching concentration detected by the inductively coupled plasma optical emission spectrometer（ICP-OES）was less than 0.1 mg/L（negligible）.It overcomes the secondary pollution caused by metal Co ion leaching.The morphology,crystal structure,structural characteristics,and structural composition of the prepared catalysts were investigated by various characterization methods.The effects of initial p H,catalyst dosage,PMS concentration,temperature,inorganic anions,and humic acid（HA）on the Cu Co₂O₄@BC/PMS system were also studied.In addition,according to the quenching experiment and EPR test,the active groups generated in the Cu Co₂O₄@BC/PMS system are·OH、SO₄^·-、O₂^·-,and ¹O₂.Combined with the XPS spectrum and EPR oxygen vacancy test analysis results,it shows that the excellent catalytic performance of the composite material.Which is due to the synergistic effect of a large number of oxygen vacancies（OVs）and bimetallic active sites of Cu and Co,and the catalytic activation mechanism is preliminarily determined.Finally,the recycling experiment shows that the catalyst can be recycled and is easy to recycle due to its magnetism.This work provides a promising strategy for activating PMS to degrade organic pollutants.