Comparative Study On Fe(?)/Fe(?) Activated Persulfate And Hydrogen Peroxide Degradation Collector Naphthalene

Naphthalene is used as collectors for copper and molybdenum ore and molybdenum ore on a large scale,and it may be discharged in large quantities in the environment,posing serious harm to the surrounding environment of the mine and human health.Therefore,it is very necessary to find a high-efficiency technology to degrade naphthalene,as well as to study the degradation mechanism and environmental fate of naphthalene under different oxidation methods.In this study,the collector naphthalene is used as the target compound to study the degradation kinetics of naphthalene in four different degradation processes(Fe(?)/PS,Fe(?)/PMS,Fenton and Fenton-like)through Ultraviolet-visible analysis spectroscopy,High Performance Liquid Chromatography and Gas Chromatography.First,analyzed and compared the oxidative degradation performance of different systems.Second,discussed some key factors(p H,amount of oxidant,anion)affecting the degradation performance of naphthalene in each system.Then,carried out free radical quenching experiments to identify the dominant free radical species in each system under different experimental conditions.Finally,combining the measured intermediate degradation products and previous research results,the degradation path of naphthalene under different oxidation methods is further proposed.The main experimental results are as follows:(1)All the degradation kinetics of naphthalene are in accordance with the first-order kinetic model,and the correlation linear coefficient is higher than 0.95.By analyzing and comparing the degradation performance of the four oxidation systems,it is found that the Fe(?)/PS system has the best degradation effect.(2)In the Fe(?)/PS system,the change of p H has no obvious effect on the removal rate of naphthalene,but the degradation rate of naphthalene for the other three systems in descending order is:p H 3.0,p H 5.0,p H 7.0,p H 9.0,p H 11.0.(3)For Fe(?)/PS and Fe(?)/PMS systems,as the amount of oxidizer increases,the removal rate of naphthalene also increases,and when the molar ratio of PS/Fe(?)/Nap or PMS/Fe(?)/Nap is 30/30/1,it reaches highest.However,in Fenton and Fenton-like systems,the removal rate of naphthalene first increases and then decreases with the increase of the oxidant dosage,and reaches the highest when the oxidant/activator/naphthalene molar ratio is 20/20/1.(4)Cl^-and HCO₃^-have inhibitory effects on four different systems.SO₄^2-presents different effects on different systems.NO₃^-has no obvious effect on the degradation of naphthalene in the four systems.(5)Free radical quenching experiments find that SO₄^·-and^·OH are the free radical species coexisting in the reaction system under acidic and alkaline conditions in the Fe(?)/PS system,while^·OH is the dominant free radical under alkaline conditions.For the Fe(?)/PMS system,SO₄^·-is the main free radical at p H 3.0,SO₄^·-and^·OH coexist at p H 7.0,and^·OH is the main contributing free radical at p H 11.0.The degradation of naphthalene in Fenton and Fenton-like systems mainly depends on^·OH.(6)The intermediate products of 1,4-naphthoquinone and phthalic anhydride were determined by GC-MS,and the possible reaction pathways of the conversion process were analyzed,and it was speculated that they mainly experienced two different degradation pathways:hydroxyl radical addition and hydrogen atom transfer.