Composition Design And Dye Degradation Properties Of Fe-Co-based Amorphous Alloys

In recent years,with the development of the printing and dyeing industry,dye wastewater has a significant pollutant of freshwater resources on Earth.The environmental pollution caused by the discharge of dye wastewater urgently needs to be addressed.In order to better protect precious water resources.Amorphous alloys have unique disordered atomic structures and homogenized compositions,without stacking fault,dislocation and other microstructure defects.Being in a thermodynamically metastable state with a large number of unsaturated sites on the surface and high residual stress inside,it is considered to be a new type of high-performance catalyst,showing great advantages in terms of dye wastewater treatment.In this study,we designed two low iron-content alloys of(Fe_0.5Co_0.5)₇₀B₂₁Ta₄Ti₅(Fe_0.5)and(Fe_0.8Co_0.2)₇₀B₂₁Ta₄Ti₅(Fe_0.8).Amorphous ribbons were prepared using a single roller melt-spinning apparatus,and were directly used for decolorization of Eosin Y（EY）solution without pretreatment.Both samples exhibited excellent degradation performances while maintaining significant cyclic stability.Compared with Fe₇₉Si₁₀B₁₁ amorphous ribbon,Fe⁰powder and Ti O₂ powder,both samples all showed higher decolorization rates and shorter degradation time.This work regulates the parameters such as reactant dosage,p H value,initial dye concentration,and cycles counts of Fe_0.5 and Fe_0.8 amorphous ribbons,and explores in detail the degradation performance of the two amorphous ribbons under different experimental conditions.The elemental distribution,microstructure,and fracture morphology of the sample surface before and after the degradation reaction are characterized in detail,thereby explaining the intrinsic degradation mechanism of amorphous ribbons.The main conclusions are as follows:（1）The Fe_0.8 amorphous ribbon was prepared by single roller melt-spinning apparatus.Through studying the effect of volumetric concentration（VC）of Fe_0.8 ribbon,the optimal degradation effect was achieved when the amount of Fe_0.8 ribbon was increased from 0.05 to0.10 g/L.However,the degradation effect was improved when the VC increased from 0.15 to0.30 g/L.After 150 min of reaction,the degradation rate of EY was as high as 96%with a fitting degradation time（t₀）of 56 min.It was found that the ribbon had the highest degradation efficiency under alkaline conditions（p H=11）,with t₀ being 49 min.The degradation efficiency of the ribbon under neutral conditions（p H=7）is superior to that under acidic condition.The surface of the ribbon was positively charged under acidic conditions,and the amount of charge increased as p H value became decreased.The ribbon was prevented from adsorbing negatively charged dye molecules onto the active sites,which led to the decline of degradation efficiency.Moreover,when the EY concentration increased from 20 to60 mg/L,the degradation rate decreased in the first 90 min,but the degradation rate of EY at different concentrations became unchanged after 150 min of reaction.When the dye concentration increased to 60 mg/L,the t₀ prolonged for 59 min,exhibiting deteriorating degradation performance.Through twenty cycles of degradation experiments,the Fe_0.8 sample has excellent usage stability.During the cyclic degradation process,the reaction activity of the amorphous ribbon was improved,and the t₀ of the sample used for the 19th was only 35 min,indicating the optimal degradation performance.It exhibited a surface"self-updating"behavior during cyclic use,which was beneficial for maintaining cycling stability.（2）The Fe_0.5 amorphous ribbon was prepared by single roller melt-spinning apparatus has flexible characteristics before and after degradation.The effect of VC on the degradation of EY is similar to that of the Fe_0.8 sample,with a maximum degradation rate of 97%and a t₀of 53 min.Through studying the effect of different p H value on the degradation of EY,it was found that it had the highest degradation efficiency under neutral conditions（p H=7）,with t₀being 53 min;the degradation efficiency of EY significantly decreases under acidic conditions（p H=3）;it has the better degradation efficiency under alkaline conditions（p H=11）than under acidic conditions.By studying the effect of concentration of EY solution on degradation performance of Fe_0.8 ribbon,it was found that when the EY concentration increased from 20 to 60 mg/L,the degradation rate decreased in the first 90 min,but the degradation rate of EY at different concentrations did not differ significantly after 180 min of reaction.When the dye concentration increased to 60 mg/L,t₀ prolonged for 58 min,exhibiting deteriorating degradation performance.Through twenty cycles of degradation experiments,it was found that Fe_0.5 amorphous ribbon remained excellently stable in terms of usability and flexibility,and the t₀ of the sixth cycle sample was only 29 min,indicating the optimal degradation performance.Based on the microstructure evolution behavior of the sample surface during the cyclic experiment,it was found that the passivation film and the fresh inner layer were rich in Ti（Ta）and Fe（Co）elements,respectively.In the process of degradation,the passive film and fresh inner layer,the exfoliation of the outer layer,exposure of the fresh surface,and regeneration of the passive film evolved alternately,which is helpful to the real-time and accurate control of photodegradation reaction.Therefore,the potential mechanism of effectively improving photodegradation activity is proposed:the introduction of nano-twins and stacking faults in the crystal phase is conducive to the transmission of photogenerated carriers;the formation of multiple superimposed heterogeneous interfaces based on entropy modulation also plays an important role in improving reaction activity.In addition,during the degradation process,the redox cycles Fe²⁺/Fe³⁺and Co²⁺/Co³⁺,forming a self-stable redox cycle process.By conducting leaching ion concentration tests on the EY solution after the first and twentieth degradation,it was found that the ion concentrations of Fe and Co meet the national emission concentration standards,proving that the Fe_0.5amorphous ribbon is an environmentally friendly reagent.