Preparation Of Iron-loaded Polyacrylic Acid-based Fiber Materials And Study Of Their Catalytic Oxidation Dye Performanc

The large amount of dye wastewater produced by the textile,printing and dyeing industries has caused great harm to human survival.Fenton technology can non-selectively mineralize organic dyes,which opens up a new direction for dye wastewater treatment.In this study,with the spinnable polyacrylic acid（PAA）as functional component and polyacrylonitrile（PAN）as reinforcing component,PAN/PAA composite nanofiber membrane was prepared using electrospinning technology.Fenton catalyst was loaded onto the PAN/PAA composite nanofiber membrane to prepare a membrane with the function of catalyzing Fenton reaction using the coordination of PAA carboxyl groups with iron ions.PAA/PAN composite nanofiber membrane with the function of rejecting iron ions was designed,which was superimposed onto the above-mentioned PAN/PAA composite nanofiber membrane with the function of catalyzing Fenton reaction using the adhesion of PAA layer in the process of electrospinning.The superimposed layer could significantly reduce the loss of iron ions during the application of fiber membranes,which could endow the fiber membranes with the ability to stably catalyze H₂O₂ to treat dye wastewater.When compared with other membranes,the composite nanofiber membrane showed many advantages for application in the field of dye wastewater treatment.Research results showed that the iron ion loading ratio of PAN/PAA composite nanofiber membrane was increased by 167%compared with pure PAN nanofiber membrane,and the total iron elution ratios of PAN nanofiber membrane and PAN/PAA composite nanofiber membrane were respectively 27 times and 6 times higher than that of fiber membranes containing superimposed layers.Due to the high loading and low eluting for iron ions,the superimposed fiber membrane could stably remove MB within 30 operation cycles,and MB removal efficiency could reach up to 97.0%.The superimposed fiber membrane had more outstanding mechanical properties and adjustable permeation flux compared with the fiber membrane prepared before superimposion.In addition,water-dispersible graphene oxide（GO）was used to replace PAN in this study,and PAA was reinforced by GO in the wet spinning process,during which iron ions was in-situ loaded onto the fiber in the spinning line.After spinning,the obtained as-spun fiber was post-treated by combining high-stretching with heat setting to prepare reusable PAA-based Fenton catalytic fiber with high strength,low shrinkage,good water resistance and low iron ion elution.The research results showed that GO doping,iron ion coordinating and suitable stretching and heat setting processes could greatly optimize the crystalline and orientation structure of the obtained fiber,giving the resultant fiber high strength,low shrinkage,and good water resistance.The introduction of GO could significantly increase the iron ion loading ratio and reduce the iron ion elution ratio of the fiber.Particularly,the introduction of GO could increase the content of divalent iron ions,which was significantly able to improve the catalytic activity of the fiber and at the same time to improve the high-stretchability of the as-spun fiber.During 40 cycles,the obtained fiber could decolorize 90.0%MB within 3 minutes,and the average concentration of eluted iron ions was only 3.2mg/L.The breaking strength of the fiber could reach as high as1.63c N/dtex,which was 40.8 times that of the as-spun PAA fiber,and the elongation at break was only 35.82%,which provided mechanical guarantee for application.