Catalytic Degradation Performance Of Fe₈₀P₁₃C₇ Amorphous Alloy On Synthetic Dyes

Since Fe-based amorphous alloys have attracted extensive attention as zero-valent iron for degrading dyes,most of the Fe-based amorphous alloys investigated for degradation are Fe-Si-B systems,or Fe-Si-B minor alloying with other elements.However,no investigation has been made on the degradation performance of Fe-P-C amorphous alloys.In this paper,we report the degradation of synthetic dyes by Fenton-like reactions using Fe₈₀P₁₃C₇ amorphous ribbons for the first time,and the catalytic degradation processes using Fe₇₈Si₉B₁₃ amorphous ribbons are investigated for comparison.The mechanism of catalytic degradation of Fe₈₀P₁₃C₇ amorphous ribbons was investigated by different characterization methods.The influence of annealing temperature on catalytic degradation performance was also investigated.This work not only provides a new high-efficient solution for wastewater remediation,but also extends the application fields for Fe₈₀P₁₃C₇ amorphous alloys.The main research contents are as follows:First of all,the degradation performance of Fe₈₀P₁₃C₇ amorphous ribbons on methylene blue by Fenton-like reaction were investigated by UV-vis.The reaction rate constant of Fe₈₀P₁₃C₇ amorphous ribbons is 0.56 min^-1,which is larger than 0.37 min^-1 for Fe₇₈Si₉B₁₃amorphous ribbons.The reaction activation energy of Fe₈₀P₁₃C₇ and Fe₇₈Si₉B₁₃ amorphous ribbons are 22.8 kJ/mol and 34.8 kJ/mol,respectively.The surface morphology of the amorphous ribbons before and after degradation reaction was investigated by means of SEM.The surface of the Fe₈₀P₁₃C₇ amorphous ribbons after degradation reaction have denser and more uniform 3D nanoporous structures than the surface of the Fe₇₈Si₉B₁₃ amorphous ribbons,which provides more channels for the electron transfer.The electronic structure of the two kinds of amorphous ribbons before and after the degradation reaction was analyzed by XPS.The galvanic cells formed due to the different strength of Fe-C bonds and Fe-P bonds exist in the Fe₈₀P₁₃C₇ amorphous ribbons,which accelerates the transfer of electrons.These all improve the efficiency of the Fe₈₀P₁₃C₇ amorphous ribbons to degrade methylene blue by Fenton-like reaction.Secondly,corrosion resistance of Fe₈₀P₁₃C₇ amorphous ribbons were investigated by electrochemical methods.It is found that the Fe₈₀P₁₃C₇ amorphous ribbons exhibit higher corrosion resistance than the Fe78Si9B13 amorphous ribbons in the acidic methylene blue solution.In addition,the Fe₈₀P₁₃C₇ amorphous ribbons also have a unique“self-renewing”behavior during the degradation reaction.After several cycles of degradation,the oxidized layers formed on the surface of the ribbons will automatically fall off,the reaction will continue on the revealing“fresh”surface.Corrosion resistance and“self-renewing”behavior make the Fe₈₀P₁₃C₇ amorphous ribbons exhibit an extremely long service life during cyclic test,even after 19 cycles,the ribbons can still maintain high catalytic degradation efficiency.Thirdly,the effects of environmental factors on degradation efficiency were investigated by changing different experimental conditions.It has been found that the Fe₈₀P₁₃C₇ amorphous ribbons are applicable in acidic methylene blue solutions,but not in neutral or alkaline solutions.The highest degradation efficiency is achieved when the initial pH=3 and the initial H₂O₂ concentration is 5 mM.The required time for decomposition of methylene blue drops with the increase of ribbon dosage or the decrease of initial methylene blue concentration.Finally,the effects of annealing temperature on the catalytic degradation performance of Fe₈₀P₁₃C₇ amorphous ribbons were investigated by means of various characterization methods.It is found that the annealing temperature has a nonlinear relationship with the catalytic degradation performance of Fe₈₀P₁₃C₇ amorphous ribbons.The enthalpy and the residue stress in the Fe₈₀P₁₃C₇ amorphous ribbons after isothermal annealing at 553 K and 593 K decrease with the structural relaxation,leading to the depression of catalytic degradation performance.However,the catalytic degradation performance of the Fe₈₀P₁₃C₇ amorphous alloy ribbons after isothermal annealing at 633 K and 673 K is better than the quenched ribbons.The reason is that the precipitation of small nanocrystals in the amorphous matrix,which promotes the formation of galvanic cells that can effectively improve the catalytic efficiency of the ribbons,overcoming the negative impacts from the reduced thermodynamic enthalpy and residue stress.The catalytic degradation performance of the isothermally annealed Fe₈₀P₁₃C₇ amorphous alloy ribbons at713⁸73 K gradually deteriorates,mainly because the surface of ribbons will oxidized with the higher annealing temperatures?above T_g?.As the degree of oxidation increases,the catalytic degradation performance continue to decrease.