Preparation Of Polyacrylic Acid-based Polymorphic Fenton Catalyst And Its Structure And Performance Stud

Polyacrylic acid（PAA）was synthesized using the mechanism of free radical polymerization with maleic anhydride（MA）as a chain transfer agent.The synthesized PAA was immersed in a dilute acid solution containing iron ions to carry out the coordination reaction between the carboxyl groups of PAA and iron ions,which could construct an ionic crosslinking network in PAA,so that the iron ion-coordinated and crosslinked PAA hydrogel was prepared.The structure of the hydrogel was characterized by SEM,FTIR and XRD,and its ability to catalyze H₂O₂to oxidatively decolorize dyes was researched with methylene blue（MB）aqueous solution as a target pollutant.The research results showed that the hydrogel catalyst could catalyze H₂O₂ to oxidatively decolorize MB aqueous solution.As coordination reaction time increased,the reusability of the hydrogel was improved.High temperature could increase the efficiency of the hydrogel to catalyze H₂O₂ to oxidatively decolorize MB aqueous solution.When the temperature reached up to80℃,the hydrogel could still catalyze H₂O₂ to decolorize MB aqueous solution within 20 minutes at the eighteenth cycle,and MB decolorization efficiency could exceed 90%,indicating that the hydrogel had excellent stability for MB catalytic decolorization.On the basis of studying the structure and performance of PAA hydrogel,we attempted to design iron ion-coordinated and crosslinked PAA fiber with better application advantages,so that Fenton method can be actually used in the field of dye wastewater treatment.First,deionized water was used as the solvent,and fully dried and pulverized PAA was dissolved in deionized water to prepare a spinning solution.A dilute acid solution containing iron ions was then used as a coagulant to spin the spinning solution into an iron ion-coordinated PAA fiber with high stretchability.Stretching and heat setting were applied to optimize the strength,dimensional stability and water-resistance of as-spun fiber.The combination of high-stretching and heat setting could thin the fiber and orient the curled PAA macromolecular chains and chain segments,and many uncoordinated carboxyl groups were at the same time exposed to the water environment during stretching and heat setting.These carboxyl groups could re-coordinate with the iron ions eluted in the methylene blue（MB）aqueous solution in the process of fiber application,which was able to minimize the loss of iron ions.Consequently,the obtained fiber exhibited highly stable activity in catalyzing H₂O₂ to decolorize MB aqueous solution.The result showed that the prepared fiber could decolorize more than 90%MB within 4 minutes during 40 cycles and did not show any obvious attenuation in MB decolorization efficiency.During 40cycles,the average concentration of eluted iron ions was only 4.89 mg/L.Additionally,the fiber prepared by combining high stretching and heat setting showed a breaking strength of 1.215 c N/dtex,which was increased by 2070%compared to that of unstretched fiber.Thanks to the enhanced strength,low leaching out of iron ions and stable catalytic activity,the obtained fiber was expected to play an active role in the field of dye wastewater treatment.