Preparation And Catalytic Degradation Properties Of Fe-Si-B Amorphous Microwires

The treatment of organic dye wastewater is an important part of water resources management.As a new type of zero-valent iron,Fe-based Amorphous alloy has great potential in the degradation of organic dyes.In this paper,based on the Amorphous microwires(Fe₇₈Si₉B₁₃^AM),the effects of Amorphous and nanocrystalline on the degradation properties of organic dyes were systematically investigated.The effect of specific surface area on the degradation performance of amorphous alloy was also investigated.Fe₇₈Si₉B₁₃ amorphous microwires(Fe₇₈Si₉B₁₃^AM)has excellent degradation performance of organic dyes.By investigating the applicability of Fe₇₈Si₉B₁₃^AM under different conditions,it was found that the degradation of Rhodamine B azo dye by Fe₇₈Si₉B₁₃^AM could be promoted by appropriately increasing the concentration of H₂O₂,increasing the amount of microfilament,increasing the reaction temperature,reducing the initial p H value of solution and reducing the solubility of initial dye.When the degradation rate was increased,the degradation process was in line with the pseudo-first-order reaction kinetics and had a low reaction activation energy（24.93 k J/mol）.Under the optimal reaction conditions,the TOC removal rate could reach 82.218%.Fe₇₈Si₉B₁₃^AM has a certain adsorption effect on Rhodamine B dye,and can degrade Methylene Blue,methylene orange and the mixture of three dyes in a short time.Meanwhile,repeated experiments show that Fe₇₈Si₉B₁₃^AM has excellent long-term reactivity.Nanocrystalline Fe₇₈Si₉B₁₃ alloys(Fe₇₈Si₉B₁₃^CM)were prepared,and the catalytic degradation of methylene blue was faster than that of Fe₇₈Si₉B₁₃^AM under the same experimental conditions,the degradation time was 1.5 times faster.The TOC removal rate was 72.227%.The degradation reaction occurs on the surface of the alloy microfilaments.Fe₇₈Si₉B₁₃^CM,as an electron donor,also has catalytic properties.Si and B elements promote the shedding of degradation products on the surface of the microfilaments by generating loose oxides on the surface of the microfilaments.However,in Fe₇₈Si₉B₁₃^CM multidirectional nanocrystalline structure,there is a certain potential difference betweenα-Fe and the intermetallic compound Fe₂B,which forms a nanoscale electrochemical galvanic cell,which increases the electron transport rate in the reaction process and improves the degradation rate.The electron transfer impedance of Fe₇₈Si₉B₁₃^CM in the electrochemical process decreases,indicating that the precipitation of nanocrystals is very conducive to the process of redox reaction,which promotes the conversion of Fe⁰ to Fe²⁺from electron loss on the surface of the microfilament.Under the same conditions,the electron transfer rate increases,which speeds up the reaction rate of degradation of organic dyes.The degradation of methylene blue by Fe₇₈Si₉B₁₃ amorphous ribbon(Fe₇₈Si₉B₁₃^AR)shows that the degradation rate of Fe₇₈Si₉B₁₃^AR is lower than that of Fe₇₈Si₉B₁₃^AM and Fe₇₈Si₉B₁₃^CM under the same conditions.The larger contact area can provide more reaction sites for the degradation reaction,and the decrease of specific surface area reduces the contact area between the amorphous alloy and the dye solution,thus weakening the catalytic degradation ability of the amorphous alloy.Therefore,increasing the specific surface area of amorphous alloy is an important way to improve the degradation performance.In addition,Fe₇₈Si₉B₁₃^AR can repeatedly degrade methylene blue solution for 25 times,and maintain a fast degradation reaction rate,which indicates that Fe₇₈Si₉B₁₃^AR also has excellent long-term reactivity.