Catalytic Degradation Of Typical Organic Pollutions From Spent Lithium Battery Cathode Materials

In recent years,the rapid rise in demand for green energy has driven the rapid development of lithium-ion batteries（LIBs）,and a large number of LIBs are used in new energy vehicles as well as portable electronic products.LIBs generate a large number of spent batteries at the end of their lifespan of up to 5 years.Spent batteries contain various types of transition metals,and the traditional methods for recycling metals in batteries at this stage have high recycling costs and tend to cause secondary pollution.It has been reported that transition metals can be applied in advanced oxidation technology for wastewater treatment with outstanding effect and wide application.Therefore,this thesis focuses on spent Li Fe PO₄（SLFP）and spent Li Ni_1/3Co_1/3Mn_1/3O₂（SNCM）,the most common spent LIB cathode materials,and uses bisphenol S（BPS）and sulfamethoxazole（SMX）as the main model pollutants to carry out the following three studies.（1）SLFP catalyzed induction of Na HSO₃（S（IV））,i.e.,SLFP/S（IV）system for the degradation of BPS.Firstly,an effect evaluation experiment was conducted to compare the performance of pristine LFP（PLFP）and SLFP activated S（IV）degradation of BPS,and the performance of SLFP was found to be more outstanding.Then the effects of initial SLFP concentration,initial S（IV）concentration,initial p H and substrate concentration on the degradation efficiency were investigated.The results showed that the degradation efficiency of BPS increased with the increase of the initial concentration of SLFP in the solution and then leveled off,with the maximum degradation rate reaching over 90%;A moderate increase in the concentration of S（IV）is beneficial to improve the degradation rate of BPS,and an excess of S（IV）will inhibit the degradation of BPS to some extent;Acidic and neutral conditions favor the BPS degradation reaction;The results of bursting experiments and electron paramagnetic resonance（EPR）indicated that^·OH,SO₄^·-and ¹O₂ were involved in the degradation of BPS as the main active species,with^·OH playing a key role;The characterization of SLFP materials before and after the reaction by inductively coupled plasma-atomic emission spectrometry（ICP-AES）,X-ray photoelectron spectroscopy（XPS）,density functional theory（DFT）and EPR revealed the existence of oxygen vacancies（O_v）and lithium defects in the SLFP materials themselves,verified the property changes of SLFP before and after the reaction,and proposed a possible reaction mechanism for the degradation of BPS by the SLFP/S（IV）system.Finally,the recycling performance and application capability of SLFP materials were explored,and the results showed that the degradation rate of BPS reached more than 70%in all four recycling experiments,indicating that SLFP has good stability and can be reused.（2）Considering that monopersulfate（PMS）was widely used in advanced oxidation technology,it was decided to investigate the effectiveness of the SLFP/PMS system in degrading SMX and its main influencing factors.The results showed that the degradation rate of SMX in the PLFP/PMS system was 78%,while the degradation rate in the SLFP/PMS system was close to 100%,the adsorption energies of SLFP and PLFP for PMS adsorption were calculated and the experimental results were further validated.The degradation rate and degradation rate of SMX increased with the increase of the initial concentration of SLFP and the concentration of PMS,while the acidic conditions were more favorable for the degradation of SMX;Sudden inactivation experiments and EPR showed that^·OH,SO₄^·-and ¹O₂ were involved in the degradation of SMX,with^·OH playing an important role;The degradation rate of SMX could reach more than 95%in all four cycles,which proved that SLFP had good stability.The mineralization rate of TOC analyzer（TOC）test SMX showed that the mineralization rate reached over 90%within 45 min,indicating that the SLFP/PMS system had good mineralization ability for organic pollutants,which was conducive to the complete removal of organic pollutants from water bodies.（3）This experiment was conducted to investigate the degradation of SMX by SNCM activating S（IV）using SMX as a model contaminant.In this study,the degradation effect of SNCM/S（IV）on SMX,the effect of single factors（initial SNCM concentration,initial S（IV）concentration,initial p H and substrate concentration）on SMX degradation were investigated.The results showed that SMX has a degradation rate of nearly 90%within 15 minutes at the initial conditions of 0.4 g L^-1 SNCM,0.3 m M S（IV）and p H 5.0.The quenching experiments and EPR showed the involvement of^·OH,SO₄^·-and SO₄^·-in the reaction process,but the contribution of^·OH was the highest.The degradation effect of SMX was little affected in the four cycles,which proved the good stability of SNCM.In addition,the degradation rates of the system for bisphenol A（BPA）,4-chlorophenol（4-CP）,sulfonyl acetate（SA）,methylene blue（MB）and p-hydroxybenzoic acid（HBA）all reached more than 75%,reflecting its good universality and degradation ability.