Fe Doped Porous Carbon Toward Boosting Peroxymonosulfate Activation For Degradation Of Organic Pollutants

Tetracycline（TC）is an antibiotic widely used in medicine,animal husbandry and aquaculture.However,most of tetracycline couldn’t be fully metabolized by human body or animals and was released into the environment,resulting in serious pollution of the environment.Because tetracycline has stable structure and bactericidal ability,traditional wastewater treatment process couldn’t effectively remove tetracycline.In recent years,the advanced oxidation treatment technology based on persulfate（PMS）has attracted more and more attention due to its higher REDOX electrode potential,longer free radical life cycle and wider p H application range.Carbonaceous materials were widely used in the activation of PMS because of their good biocompatibility,large surface area and adjustable electronic properties.Doping nitrogen atoms in the carbon skeleton can effectively change the chemical inertness of the carbon material and generate more active sites,thus significantly improving the catalytic capacity of the carbon material.In addition,various iron-based materials were being widely used in PMS activation due to their low cost,wide range of sources and safety and non-toxicity.Therefore,the new composite prepared by combining iron nanoparticles with nitrogen-doped carbon materials can not only effectively improve the degradation efficiency of organic pollutants by PMS,but also has the characteristics of low magnetic recovery and metal leaching rate,which can avoid causing secondary pollution.Therefore,a series of iron-nitrogen doped carbon-based materials were prepared in this paper,and their properties and degradation mechanism were studied by activating PMS to degrade tetracycline.Related work contents are as follows:（1）Nitrogen-doped mesoporous carbon nanosheets（N-MCNs）were synthesized by high temperature pyrolysis using glucose as carbon source and dicyandiamine as nitrogen source.Among them,the material（N-MCNs-800）calcined at 800℃could efficiently remove tetracycline hydrochloride,and remove 86.2%TC（20 mg/L）within15 minutes.Its pseudo first order reaction rate constant k was 0.268 min^-1,which was38.3 times of that without nitrogen doping.Through N doping,the specific surface area of carbon material is increased and the active site is increased,thus significantly improving the activation performance of the activator to PMS,and greatly improving the removal efficiency of TC pollutants.Finally,TC intermediates were detected and a possible TC degradation pathway was proposed.（2）Fe-N-DSC was synthesized from biocarbon derived from discarded durian shells and activated PMS to degrade tetracycline using a low-cost strategy.Under optimal conditions,0.1 g/L of Fe-N-DSC activated 0.2 mmol/L of PMS degraded90.74%of TC（20 mg/L）in 10 minutes.At the same time,the stability and safety of Fe-N-DSC in the activation of PMS were further proved by cyclic experiments and ICP determination of iron ion.The quenching experiment and electrochemical experiment show that the surface free radical and electron transfer ability play a major role in the activation of Fe-N-DSC/PMS system.The main active sites of Fe-N-DSC are pyridine nitrogen,graphite nitrogen,sp²hybridized carbon and C=O group.