Study On The Degradation Performance And Mechanism Of Azo Dyes By Fe-based Amorphous Alloy

Azo dye wastewater will not only cause environmental pollution,but also produce fragrance,which is highly toxic,carcinogenic and even explosive.In recent years,Fe-based amorphous alloys have become very attractive metal catalysts in sewage remediation because of their low price,no pollution to the environment,reusability,and high decomposition efficiency.Although Fe-based amorphous alloys have excellent degradation properties for azo dyes,there are still many problems to be further studied.In response to this,the following two works have been done in this thesis:(1)In the first work,Fe₈₀Si₁P₁₀C₉ amorphous melt-spun ribbon(MSR),ball milling powder(BMP)and multistage atomized powder(MAP)are prepared,and a comparative study of their performance on degrading methylene blue(MB)solution by Fenton-like reaction is carried out to explore the effect of the surface morphology on the degradation performance of Fe-based amorphous alloys.The results indicate that,under the same test conditions,the degradation efficiency of MB by BMP,MSR and MAP decreases in turn.The high degradation efficiency of BMP can be attributed to the large specific surface area and surface unevenness.Despite the large specific surface area,the formation of an oxide layer on the surface in the preparation process and a smooth surface of the as-prepared MAP allow the degradation reaction to occur only in limited locations,which results in the lowest degradation efficiency of MAP among the three samples.Among the three samples,MSR has the longest service life in cyclic testing,which may be related to the formation of flower-like structure on the surface of MSR during degradation.For BMP and MAP,as the number of degradation cycle increases,the reaction products will slowly deposit on the surface of the sample,thus leading to a poor service life.This study indicates that the surface morphology of Fe-based amorphous alloys has a significant effect on their azo dye degradation performance.(2)In the second work,we studied the degradation of methylene blue(MB)solution by Fe₈₀P₅C₁₅(P₅C₁₅),Fe₈₀P₁₀C₁₀(P₁₀C₁₀)and Fe₈₀P₁₅C₅(P₁₅C₅)amorphous alloy ribbons to investigate the effect of metalloid element content(P/C ratio)on the degradation performance of Fe-P-C amorphous alloys.The experimental results show that,for MB degradation under the same conditions,P₅C₁₅ has the fastest reaction rate constant and the lowest reaction activation energy,followed by P₁₅C₅ and P₁₀C₁₀,indicating that the degradation efficiency of P₅C₁₅ is the best.P₅C₁₅,P₁₀C₁₀ and P₁₅C₅amorphous alloy ribbons all form a 3D nanoporous structure on the surface during the degradation reaction.Among them,the flower-like structure on the P₅C₁₅ surface is fluffier and more porous,which provides more channels for electron diffusion,so it is conducive to obtain high degradation efficiency.The cycle test shows that the reuse performance of P₅C₁₅,P₁₅C₅ and P₁₀C₁₀ decreases in turn,and the long service life of P₅C₁₅ and P₁₅C₅may be attributed to the formation of more porous structure on the surface during the degradation process.The analysis of XPS results showed that the P₅C₁₅,P₁₀C₁₀ and P₁₅C₅ amorphous alloy strips participated in the formation of the reaction-C=O-area increased by 10.96%,5.88%and 6.51%,respectively.It can be seen that the Fe-C fracture of P₅C₁₅ is the most,followed by P₁₅C₅,and P₁₀C₁₀ is the least.The EDS measurement results found that the P loss in P₅C₁₅ before and after the reaction was the largest,followed by P₁₀C₁₀ the smallest.The loss of C and P leads to the formation of galvanic cells between the strong Fe-C bond and the weak Fe-P bond.Therefore,the number of galvanic cells formed during the degradation reaction of P₅C₁₅,P₁₅C₅ and P₁₀C₁₀ decrease sequentially,and the formation of galvanic cells can promote The degradation reaction progressed,which explained the reason why the degradation efficiency of P₅C₁₅,P₁₅C₅ and P₁₀C₁₀ amorphous alloy strips on MB decreased in turn.