Polydopamine/polyethyleneimine Composite Non-woven Fabrics Strengthened Iron-activated Persulfate Oxidative Degradation Of Dyes

Fe²⁺ activated persulfate?PS?has the advantages of low cost,high catalytic activity and easy removal,so it is widely used in water treatment technology.However,too much Fe²⁺ could easily lead to quenching of SO₄?-,while too little Fe²⁺ could lead to stagnation of the reaction system.In this study,a kind of polydopamine/polyethylenimine-functionalized polypropylene nonwovens?PDA/PEI@PP?with good hydrophilicity were prepared to improve the catalytic degradation ability of Azorubin?ARB?by Fe²⁺/PS system.The mechanism of oxidative degradation of ARB in Fe²⁺/PS system enhanced by PDA/PEI@PP was studied from three aspects: coordination of Fe²⁺,reduction of Fe³⁺ and activation of PS.?1?The effects of initial DA concentration,preparation time and PEI concentration on polydopamine loading were systematically studied.Meanwhile,the effects of different preparation conditions on Fe²⁺ coordination complexation and reduction rate of Fe³⁺ reduced to Fe²⁺ were studied.The results showed that PEI concentration had a greater effect on Fe²⁺coordination complexation,and the better the effect with Fe²⁺ coordination complexation was with the increase of PEI concentration.FTIR,XPS and SEM were used to analyze the main functional groups and microstructure of the materials.The results showed that the material surface was rich in catechol group and quinone group,and PDA/PEI was uniformly loaded on the surface of PP fiber.?2?Through controlled experiments,it was found that PDA/PEI@PP and PDA@PP could degrade ARB by activating PS.It was speculated that the catechol group and quinone group on the surface of the material generated quinone anion radicals in the reaction liquid,which activated PS to generate sulfate free radicals and effectively degraded ARB.FTIR and XPS were used to detect PDA/PEI@PP and PDA@PP surface functional groups before and after PS activation.It was found that the content of catechol group decreased and the content of quinone group increased after PS activation,indicating that catechol group and quinone group were involved in the activation reaction.It was found that ?OH and SO₄^?- existed in PDA/PEI@PP /PSsystem by ESR,indicating that PDA/PEI@PP could activate PS to produce SO₄^?-.?3?The degradation rate of ARB,consumption of PS,first kinetics and ESR in PDA/PEI@PP /Fe²⁺/PS and Fe²⁺/PS systems were analyzed in the experiment.The results showed that the introduction of PDA/PEI@PP enhanced the activation of PS,which improved the degradation rate of ARB and reaction rate.The effects of p H and PEI concentration on PDA/PEI@PP activation of PS were discussed,and the recycling times of PDA/PEI@PP in Fe²⁺/PS were also discussed.