| Water pollution has always been an important environment problem restricting human development and threatening human health,so sewage treatment has been widely concerned and studied.In actual production and life,sewage comes from a wide range of sources,including industrial wastewater,domestic sewage,commercial sewage and surface runoff,and often contains inorganic,organic,microbial and other complex pollutants.Therefore,people hope to get a class of sewage treatment materials with low production and use cost,can widely cope with a variety of pollution types.Due to the characteristics of high specific surface area,high porosity and adjustable pore structure,nanofiber materials have good application prospects in sewage treatment matrix materials due to their controllable morphology and structural characteristics,easy modification,modified functionalization and processing.Zinc oxide nanowires（ZnO-NWs）have super-wetting properties,photocatalytic ability,good antibacterial and heat resistance,and have considerable application potential as surface modification materials in a variety of wastewater treatment.Hierarchical structured nanomaterials based on nanofiber materials and nanowires are expected to combine the structural and functional advantages of nanofiber and nanowires to give the materials better water treatment performance.Based on zinc oxide nanowire modified micro nano fiber materials,this paper constructs different multilevel structure nano fiber membranes and micro nano fiber composite membranes,and explores their application potential as wastewater treatment membranes.The morphology,wettability,oil-water separation,heavy metal adsorption,photocatalytic dye degradation,single-guided water and antibacterial properties of several nano-fiber membranes and micro-nano-fiber composite membranes were systematically studied.The main research contents and conclusions are as follows:（1）Polyvinylidene fluoride nanofiber membrane matrix was obtained by solution jet spinning,and ZnO-NWs were modified by hydrothermal method to obtain superhydrophilic multistage nanofiber membrane.The relationship between the morphology and structure of the superhydrophilic film and its wettability and oil-water separation performance was investigated.The results show that the nanofiber matrix with fluffy structure and ZnO-NWs with uniform and effective modification are obtained.The material has the characteristics of super hydrophilic/hydrophobic underwater wetting.In the process of separating free oil and water,the flux of the membrane reached 12,960.77±325.04 L·m-2·h-1·bar-1 and the separation efficiency reached 99.7%.In addition,the membrane also showed high flux(about 8000 L·m-2·h-1·bar-1)and good separation efficiency（>97%）for various oil-water emulsions.（2）In order to solve the defect of decreasing hydrophilicity of ZnO-NWs when exposed to air,the self-polymerization of dopamine in alkaline solution was used to generate the polydopamine layer which evenly wrapped the nanowire and nanofibers,and the durable super hydrophilic PDA/ZnO-NWs/PVDF nanofiber membrane was obtained.The wetting attenuation of ZnO-NWs modified nanofiber membrane was studied and the wetting attenuation model was summarized.The study showed that the nanoscale polydopamine layer uniformly modified the nanofiber membrane,which greatly improved the stability of super hydrophilic air resistance and high temperature resistance.Polydopamine and ZnO-NWs formed a co-effect structure of adsorption and photocatalytic degradation,which greatly improved the adsorption capacity of copper ions（71.3%,57.0 mg/g）and photocatalytic degradation capacity of Rhodamine B（90.4%,6 mg/g）.（3）Inspired by the wetting attenuation model of nanofiber membrane in study（2）,the super-hydrophilic nanofiber membrane was covered with electrostatic spinning polyvinylidene fluoride microfiber membrane,and silver nitrate was added to load the hydrophobic layer with nano silver,and a single guide water composite membrane with antibacterial properties was constructed.The results show that the nanosilver content and thickness of the hydrophobic layer of the composite film have a great influence on the morphology and structure.The monoconductivity of the hydrophobic layer can be adjusted by adjusting the thickness of the hydrophobic layer,and the thickness of the hydrophobic layer will reduce the monoconductivity of the composite fiber membrane.With the increase of the thickness of the nanofiber layer loaded with Ag NO3,the antibacterial performance was improved,and the results showed that the monoconductive water guide material showed good antibacterial performance under the premise of reducing metal dissolution.The micro-nano-fiber membrane modified by ZnO-NWs in this study can be used in water treatment technologies such as oil-water separation,heavy metal adsorption,photocatalytic degradation,single guide water,etc.,providing a new idea for complex sewage comprehensive treatment materials. |
