Studies On Electrospinning Preparation And Water Purification Performance Of Heterostructured Nanofibers

Water contamination is one of the most serious environmental issues facing humanity.Inorganic materials are considered as promising candidates for water treatment due to the advantages of environmental friendly,better water purification performance and high recovery rate.In this dissertation,La₂O₃,Ni-La₂O₃,Ni-Nd₂O₃,Ni-Sm₂O₃and Ni-Ce O₂nanofibers were prepared by electrospinning method.The smart design of heterojunction enables these nanocomposite fibers excellent antibacterial and adsorptive performance,which is further improved by unique atomic structure of Lanthanide.Our work opens a new avenue for the design of high performance adsorbents.La₂O₃nanofibers was prepared and its antibacterial properties were investigated.The electrospun La₂O₃nanofibers was slender and continuous,stacked by flaky grains.The resultant fibers showed 95%inactivation rate for high concentration E.coli within100 min under low nanofiber loading.This sterilization process was facilitated by the combination of La³⁺and extracellular nuclease enzymes,which could efficiently inhibit the reproduction of bacteria.The heterogeneous Ni-La₂O₃nanofibers was developed using an electrospinning technique.The optimal adsorption activity was achieved when the Ni concentration was kept at 5.5 at.%.The nanocomposite fibers can rapidly remove various detrimental micropollutants with absorption rate constants hundreds of times greater than those of inorganic materials and activated carbons.In addition,the NLO nanofibers can be re-generated several times by a soft methane wash process maintaining stable performance,which is economically competitive.The positively charged layer formed at the unique heterointerface generated electron interaction with electron-rich group on organic pol-lutants,endowing the fibers excellent adsorption properties.Meanwhile,the positively charged interface can also produce electrostatic attraction with phosphate group on the cell wall.The resulted permeability change,ion channels and transmembrane pores in the bacterial cell wall led to the cytoplasmic content leakage and cell death.Combined with the destruction of genetic material by La³⁺ions,the antimicrobial performance of this heterogeneous fibers was greatly improved.The influence of rare earth elements on the adsorption performance was studied by the fabrication of various rare earth metal oxide and Ni heterogeneous nanofibers.Under the same experimental conditions,their pollutant removal efficiency and cyclic performance were evaluated.Through the study of adsorption kinetics and thermodynamics,it is proved that the adsorption reaction is a single-layer adsorption process controlled by electrons interaction.The adsorption rate constants increased exponentially with increasing atomic number of rare earth elements,demonstrating that the attraction of nuclear enhanced by effective nuclear charge could promote the adsorption process.The effect of valence change in the rare earth elements on adsorption properties was investigated.Ni-Ce O₂nanofibers were prepared by electrospinning method.The defect caused by Ce³⁺in Ni-Ce O₂nanofibers affects the formation and stability of space charge layer,resulted in the decline of adsorption performance.Thus,the stability of functional interface is of virtual importance for adsorption ability.