Research On Properties And Influencing Factors Of Fe-based Amorphous/Nanocrystalline Alloys Towards Azo Dye Degradation

Degradation and purification of wastewater are of great significance for environmental protection and sustainable development.Dyeing wastewater,containing azo dyes,is one of the most refractory wastewater.Recently,researchers have reported that Fe-based amorphous alloys have better degradation capability towards azo dyes than their crystalline counterparts and conventional crystalline zero-valent iron?ZVI?.However,performances of Fe-based amorphous alloys and its derivative Fe-based nanocrystalline alloys and their influencing factors are still lacking in full understanding.Orange ?,a typical azo dye,was selected as the contaminant to investigate the main influencing factors of the degradation capability of Fe-based amorphous/nanocrystalline alloys.The related mechanism was al so discussed.(Fe_73.5Si_13.5B₉Nb₃Cu₁)_91.5Ni_8.5 multiphase nanocrystalline alloy ribbons?CR-??were prepared by annealing treatment at a temperature above the second crystallization temperature.Unlike previously reported results,CR-? has better degradation properties than its amorphous counterpart s.CR-? has a wide annealing treatment process window,good environmental applicability,and good long-term reactivity?maintain high reactivity after 7 cycles and increased to 25times with ultrasonic vibration?.In particular,the degradation efficiency under alkaline conditions?pH=10?is as high as 97%.The high performance of CR-? can be attributed to its nanoscale chemical inhomogeneity which give s rise to nanoscale galvanic cell effect and accelerates the?-Fe nanocrystals to lose electrons to promote the degradation of Orange ?.Moreover,the three-dimensional nanoporous structure formed by the retained intermetallic compounds after the selective corrosion of?-Fe and the flower-like nanostructure products also contribute to the high performance of CR-?.Fe₈₁Si₄B₁₄Cu₁ amorphous ribbon with nanoscale?3⁵ nm?Cu-rich cluster regions,i.e.Fe-based amorphous ribbon with nanoscale chemical inhomogeneity?Fe-AR-NCI?,was prepared.Fe-AR-NCI exhibited excellent degradation capability,good environmental adaptability,espe cially high degradation efficiency at pH=10,and excellent long-term reactivity with high performance up to 45 cycles which is better than other reported results.The excellent long-term reactivity of Fe-AR-NCI results from its self-cleaning property that the reacted region and the precipitated corrosion products can self-peel off during the cycle experiment without acid wash or ultrasonic vibration which is usually applied to refresh the aged ZVI.with addition of Ni element,degradation capability of(Fe_73.5Si_13.5B₉Nb₃Cu₁)_100-x00-x Ni_x?x=0?1?3?5?8.5?10?amorphous ribbons first increases and reach best performance at X=8.5,then decreases.The residual internal stress in the amorphous ribbon is favorable for the formation of stress gradient cell effect,increasing the reactive sites and promoting the degradation capability of amorphous ribbon.After immersing in the Orange ? solution,there are three-dimensional flower-like iron oxide nanostructures attached to the surface of CR-?,i.e.CR-?+3D-FNs.It has good adsorption effect on hexavalent chromium which will benefit for the treatment of wastewater containing heavy metal ions.