Fe₃O₄-Based Magnetic Composites And Their Applications In Dye Wastewater Treatment And Lithium-ion Batteries

Iron oxide magnetic composite materials have attracted much attention owing to their wide applications in various fields, such as magnetic recording, microwave absorption, targeted drug, MRI, catalysts and energy storage/conversion fields.In this thesis, Fe3O4/PANI magnetic composite as catalyst ultrasound-assisted degradation of methyl orange. Firstly, Fe3O4 nanoparticles were synthesized by solvothermal method. FeCl3·6H2O as raw materials, ethylene glycol as solvent and reducing agent. Then, Fe3O4/PANI composites prepared by in situ polymerization method. The synthetic material were characterized with XRD, SEM, TEM, FT-IR, Zeta-potential and SQIM measurements. Results of tests that:(1) Synthesized Fe3O4/PANI composite having a core-shell structure, high saturation magnetization, superparamagnetic, while S, Cl co-doped of the polyaniline shell.(2) Fe3O4/PANI has a high absorption capacity for methyl orange, the maximum absorption capacity of 128.7 mg g-1(25℃); The isotherms and kinetics of MO absorption with Fe3O4/PANI follow the Langmuir model and the pesudo-second-order model, respectively.(3) Ultrasound-assisted, the degradation behavior of MO with Fe3O4/PANI conforms to a combinational model that the first absorption after catalytic degradation: the absorption and degradation process follows the pseudo-second-order adsorption model and the pseudo-first-order degradation model, respectively.(4) The percentage of sonocatalytic degradation of MO with Fe3O4/PANI is about 4.8,8.8, and 5.7 times that with Fe3O4, dedoped Fe3O4/PANI, and ultrasonication alone, respectively.Fe3O4/C nanosheets aggregates were prepared by a solvothermal method combined with calination method. Fe(acac)3 and glycerol-ethanol mixture as raw material and reaction medium, respectively. Influence factors of nanosheets were explored, include the reaction medium, solvent ratio, reaction time, amount of PVP K-30, treatment of sample. The samples were characterized with XRD, SEM, TGA/DSC-. BET and electrochemical performance measurements. Results of tests that:(1) Glycerol-ethylene glycol, glycerol-ethanol as a reaction medium can generate the nanosheets precursor, glycerol concentration play an important role on formation the follow Fe3O4/C nanosheets aggregate.(2) The charge-discharge measurements show that Fe3O4/C nanosheets initial discharge capacity is 1434 mAh g-1, the discharge capacity of the fifth cycle of 402 mAh g-1, indicate capacity fade serious.When cycle to 20 and 50 laps, theoretical capacity of 368 and 312 mAh g-1, respectively. It indicate that from 20 to 50 laps relatively good capacity retention.