Recovery Of Negative Electrode Of Lithium-ion Battery To Construct Zero-valent Iron-copper Bimetal Loaded With Graphite And Its Performance Evaluation

Since the lithium-ion battery was developed and put into the market,it has developed rapidly because of its advantages such as high specific energy,stable discharge voltage,small self-discharge,good cycle performance and no memory effect.It is widely used in mobile phones,computers and other electronic products,medical and health care,electric vehicles and other related industries.With the wide application of lithium-ion batteries,a large number of waste lithium-ion batteries have dual properties of hazardous waste and available resources.The efficient recycling of waste lithium-ion batteries is of great significance to environmental protection and resource regeneration.In this paper,graphite supported zero valent iron copper bimetallic composites were prepared by carbothermal reduction reaction after the anode materials were pretreated by mechanical ball milling.The structure and composition of the composites were studied by various characterization methods,and p-chlorophenol（4-CP）in wastewater was degraded by the composites.The main conclusions are as follows:（1）The best ball milling conditions for spent lithium ion battery anode materials are as follows:the speed of the ball mill is 800 rpm,the ball-to-battery ratio is 140:1,and the milling time is 5 hours.XRD results show that the ball milled product is relatively pure and has no excess impurities.SEM results show that the graphite particles after ball milling are more dispersed,and the copper powder after the copper foil is broken more uniformly covers the surface of the graphite particles.（2）The best preparation conditions for the graphite-loaded zero-valent iron-copper bimetal are as follows:the mass ratio of the ball-milled mixture to Fe₂O₃ is 1:2,the calcination temperature is 1000℃,and the retention time is 2 h.The results of XRD,SEM-EDS,TEM and BET show that the zero valent iron in the graphite supported zero valent iron copper composite is micron sized and ellipsoidal particles,and copper powder is densely distributed on the surface of zero valent iron particles and graphite.（3）The best experimental conditions for graphite-loaded zero-valent iron-copper bimetallic reduction degradation of 4-CP are as follows:the dosage of material is 0.4 g/L,the initial p H is 3,the temperature is 25℃,4-CP concentration is 10 mg/L.The degradation process of 4-CP was affected by different proportion of sample,initial p H,dosage,temperature and 4-CP concentration.PH has a great influence on the removal of 4-CP.when p H is 3,the solution is in an acidic environment,and zero valent iron and copper on its surface produce galvanic effect,which aggravates the corrosion of zero valent iron and produces more Fe²⁺and H₂.H₂ adsorbs on the surface of graphite material and generates more reductive active hydrogen under the catalysis of copper,thus increasing the removal efficiency of 4-CP.（4）The best experimental conditions for graphite-loaded zero-valent iron-copper oxidative degradation of 4-CP are as follows:the dosage of material is 0.2 g/L,the initial p H is 3,the temperature is 25℃,a concentration of 10 mg/L of 4-CP and a concentration of 0.5mmol/L of H₂O₂,4-CP can be completely removed 100%.Factors such as different proportions of samples,solution p H,dosage,temperature,4-CP concentration and H₂O₂concentration will affect the removal of 4-CP.PH and H₂O₂ have a greater impact on 4-CP.As the concentration of H₂O₂ increases,the degradation rate of 4-CP becomes faster.A concentration of 0.5 mmol/L of H₂O₂ can completely degrade 4-CP.When the initial p H of the solution is 3,the removal rate of 4-CP is 100%.When the p H is 7,10,the final removal rate is4.45%and 2.21%,which indicates that the degradation experiment is the best in acidic environment.