Efficacy And Mechanism On Cobalt-decorated Biochar’s Capacity To Activate Peroxymonosulfate For Sulfamethazine Removal In Aqueous Solution

Sulfate radicals-based technology was widely used to mineralize organic pollutants,generating radicals by activating persulfate(including peroxymonosulfate and peroxydisulfate)oxidants through catalysts.Biochar with merit of electrochemical structures(surface moieties,carbon matrix structures)could play as an electron donor/acceptor/mediator participating in various redox reactions.Although biochar could activate persulfate to produce sulfate radicals,the activation ability of biochar is limited.Cobalt nanoparticles could efficiently activate peroxymonosulfate,but they tend to agglomerate and lead to secondary pollution.In this study,sulfamethazine was used as a model pollutant and a cobalt-loaded biochar composite material was prepared to improve the activity ability of biochar on peroxymonosulfate.The carbon matrix helped to disperse the cobalt particles,effectively inhibit cobalt leaching,and reduce secondary pollution.The effects of the dosage of catalyst and oxidant,pyrolysis temperature,cobalt loading,and pH of the solution on the use of cobalt-loaded biochar were optimized.XRD,XPS,and Raman are also used to characterize and explore the reaction mechanism.The main findings are as follows:1.The cobalt-loaded biochar could efficiently activate peroxymonosulfate to degrade sulfamethazine.The optimal dosages of cobalt-loaded biochar and peroxymonosulfate are 400 mg/L and 0.06 m M,respectively.As the dosage of cobalt-loaded biochar increased,the degradation efficiency of sulfamethazine increased,but excessive dosage of peroxymonosulfate inhibited the reaction rate.There is an optimal loading of cobalt,and excessive cobalt would generate more free radicals,causing self-quenching reaction.The cobalt-loaded biochar obtained at800°C had the best activation effect on persulfate.The pyrolysis temperature affects the removal efficiency by influencing the crystal types and phase of the loaded cobalt.The profitable solution pH was 8 and 10 mg/L pollutants could be 100% degraded within 60 minutes.2.After the catalyst was reused 3 times,the pollutant removal efficiency was reduced less than 10%.The leaching cobalt ions was lower than 0.05 mg/L.LC-MS was utilized to explore the degradation pathway of sulfamethazine.The cobalt-loaded biochar was applied to degrade sulfamethazine in the simulated groundwater and showed acceptable catalytic performance.3.The control experiment of the blank biochar showed that the cobalt loaded on the biochar played a main role when activating the peroxymonosulfate.In addition,cobalt and biochar had a synergistic catalytic effect,and the synergistic effect was based on the graphite-like structure of the carbon matrix,which could mediate the electrons between cobalt and peroxymonosulfate and improve the efficiency of electron transfer and free radicals generation.