Study On Secondary Material Preparation From Cathod Of Spent Lithium Ion Battery And Its Application In Antibiotic Degradation

Spent lithium ion batteries（LIBs）is a kind of solid waste with huge quantity and rich metals.When it’s stacked for a long time without treatment,the intern al metals and organic components will be released into surrounding environment,causing serious soil,water and air pollution,and ultimately endangering human health.The recycling of spent LIBs can not only alleviate the increasing environmental pressure,but also recover scarce metal resources,which is of great significance to the construction of resource-saving and environmentfriendly society.In this paper,taking the cathode of spent LIBs as the research object,three kinds of functional materials were prepared by treating the cathode leaching solution in different ways,and the degradation performance in tetracycline antibiotics of these materials were studied in detail.According to the material characterization,degradation experiment and mechanism analysis,the internal mechanism of antibiotic degradation was revealed,and it’s provided a new idea for recycling the positive electrode of spent LIBs.The main results are as follows:（1）Preparation of Co-S composites by treating cathode leaching solution with sodium sulfide（Na2S）.The material component is complex,which is contains different chemical states of cobalt and sulfur.In addition,the material exhibits good ability of tetracycline degradation,and the degradation process depends on the oxidative holes,which are generated on the surface of the material.At 25℃,alkaline condition and loadings ratios of 1.6g/L,the degradation rate of tetracycline can reach 98.6%.（2）Clear structure and higher stability material Co1-xS@CN were prepared by using sodium diethyldithiocarbamate（C5H10NNaS2）to treat cathode leaching solution and calcined intermediate product in oxygen-free environment.The material contains carbon layer and hexagonal Co1-xS nanoparticles,in which high-valence cobalt（Co3+）occupies a high proportion,and S,N are better doped in carbon layer.Meanwhile,the experiments show a degradation ability of material on tetracycline,aureomycin hydrochloride and oxytetracycline.At pH=10,loadings ratios of 1.5g/L and room temperature,the degradation rate of three antibiotics can reached 98.4%、99.3%、87.9%,respectively.Moreover,the mechanism analysis showed that,conversion process of Co3+/Co2+on the surface of materials can produced oxidizing holes,which directly degraded antibiotics.These surface electrons can also combine with dissolved oxygen to generate ·O2-and ·OH,further improving the degradation ability.（3）Prepared an environmentally friendly and stable material Co1-xS@CN/g-C3N4 by supported Co1-xS@CN material on g-C3N4.The material has a flake nanostructure and Co1-xS@CN is organically bound to g-C3N4.The degradation experiments show that,after the activation of visible light,the material can generate oxidizing holes,·O2-and ·OH.These active substances can promote the demethylation,decarbonylation and carbon-carbon bond fracture of antibiotic molecules,so as to achieve the goal of efficient and stable degradation of tetracycline antibiotics.