Dye Degradation Properties Of Fe-based Amorphous/Nanocrystalline Alloys

Iron-based amorphous/nanocrystalline alloys have lower reaction activation energy than tradi-tional crystalline alloys,and thus have a broad application prospect in the field of synthetic dye deg-radation.At present,it has been widely accepted that the heterogeneous microstructure induced by anealling process and the large specific surface area are beneficial to improve the degradation perfor-mance of the catalyst.This subject concentrates on the effect of annealing on the degradation perfor-mance of Fe₈₁Si₂B₁₀P₆Cu₁ and(Fe₈₀B₁₃C₇)₉₉Cu₁ amorphous alloys,and researches the mechanism of high degradation efficiency of Fe₈₁Si₂B₁₀P₆Cu₁ nanocrystalline powders in alkaline solutions and the degradation performance of Fe₇₈Si₉B₁₃amorphous powders.This work mainly includes:1.The degradation performance towards methylene blue of Fe₈₁Si₂B₁₀P₆Cu₁ amorphous ribbons（FeSiBPCu-aq）and their single/multiple nanocrystalline counterparts in Fenton-like reaction is studied,and the reasons for their different performance are analyzed.It is found that there is a competitive relationship between the heterogeneous microstructure and the surface oxide film.The galvanic cells formed in the Fe₈₁Si₂B₁₀P₆Cu₁ amorphous ribbons（FeSiBPCu-aq）improve their catalytic ability.Alt-hough the single nanocrystalline ribbons（AN-703）have more zero-valent irons on the surface and more galvanic cells,the superficial iron phosphate and silica oxide layer which has good corrosion resistance make their catalytic performance comparable to that of Fe₈₁Si₂B₁₀P₆Cu₁ amorphous ribbons.Multiple nanocrystalline ribbons（AN-803）with multiple nanocrystallines have a decreased catalytic efficiency due to the stable intermetallic compound Fe₃P_0.37B_0.63 and the enrichment of iron phosphate and silica on the surface.Besides the reusability of Fe₈₁Si₂B₁₀P₆Cu₁ amorphous ribbons is studied.It takes less than 30 minutes to finish the degradation process even after 20 cycles.2.The effect of adding Cu into Fe₈₀B₁₃C₇ amorphous alloys on their degradation performance and the effect of annealing treatment on(Fe₈₀B₁₃C₇)₉₉Cu₁ amorphous ribbons’electrochemical prop-erties and degradation properties is investigated.It takes 30 minutes for(Fe₈₀B₁₃C₇)₉₉Cu₁ amorphous ribbons to degrade 250 m L of 20 mg/L Acid Orange 7 solutions,20 minutes faster than Fe₈₀B₁₃C₇amorphous ribbons.The corrosion potentials of(Fe₈₀B₁₃C₇)₉₉Cu₁ amorphous ribbons after annealing at different temperatures are with small differences,but their charge transfer resistances were quite different.Compared with the amorphous ribbons,the charge transfer resistance of the 403-5 ribbons,which was prepared by annealling(Fe₈₀B₁₃C₇)₉₉Cu₁ amorphous ribbons at 403 K for 5 min,decreases and thus further promotes their degradation efficiency,leading their reaction rate constant increases from 0.094 min^-1 to 0.103 min^-1.3.The degradation performance of Fe₈₁Si₂B₁₀P₆Cu₁ nanocrystalline powders and ball-milled Fe₇₈Si₉B₁₃ amorphous powders（FeSiB-BM powders）is studied.The degradation mechanism of Fe₈₁Si₂B₁₀P₆Cu₁ nanocrystalline powders under alkaline conditions is also analyzed.The reaction ac-tivation energy of Fe₈₁Si₂B₁₀P₆Cu₁ nanocrystalline powders is only 8.1 k J/mol,which is much lower than that of Fe₈₁Si₂B₁₀P₆Cu₁ nanocrystalline ribbons.Fe₈₁Si₂B₁₀P₆Cu₁nanocrystalline powders can still maintain good catalytic activity in alkaline solution because the dissolution ofα-Fe grains weakens the effect of p H_pzc on the adsorption of azo dye molecules.It is found that mechanical ball milling and spark plasma sintering processes can activate Fe₇₈Si₉B₁₃ amorphous powders and effectively improve its catalytic degradation performance.The ball-milled Fe₇₈Si₉B₁₃ amorphous powders（FeSiB-BM powders）can degrade AO7 solutions quickly under a wide range condition of p H=3-10,C₀=20-400mg/L and T=298-318 K.In addition,ball-milled Fe₇₈Si₉B₁₃ powders can be reused at least 9 times,showing a good catalytic performance.