铁基非晶条带催化降解性能的退火晶化调控机理

Annealing crystallization control mechanism of catalytic degradation properties of Fe-based amorphous ribbons

非晶合金是原子结构长程无序的亚稳态材料,具有优异的催化降解性能,同时也很容易发生晶化,但晶化对催化降解性能的影响机理目前尚不明确.本文研究了退火晶化对Fe-Si-B-Cu-Nb工业非晶条带微观结构及其对酸性橙7催化降解性能的影响.研究发现:经460—580℃退火后,条带的催化降解性能大幅下降,其反应速率常数低于0.01 min–1,α-Fe析出相导致其非晶结构的破坏,降低了羟基自由基的形成速率;而经过650—700℃退火后,条带的催化降解性能显著提高,反应速率可提升至退火前的3.77倍,降解15 min时的脱色率达99.22%,为退火前的1.12倍,催化降解性能的提高得益于晶化相与金属化合物间的原电池效应及富集Cu团簇和零价铁之间的置换反应.本研究揭示了退火晶化对偶氮染料的铁基非晶条带催化降解性能的作用机理,为利用老化的铁基非晶工业条带处理印染废水、实现“以废治废”,提供了有益的理论与实验支撑.

Amorphous alloys are meta-stable materials with long-range disordered atomic structure,which have excellent catalytic degradation performance and are also susceptible to crystallization,but the mechanism of the effect of crystallization on their catalytic properties has not been clarified.Therefore,the effect of the annealing crystallization process on the microstructure of Fe-Si-B-Cu-Nb industrial amorphous ribbons and their catalytic degradation properties for acid orange 7 are investigated in this work.It is found that the catalytic degradation performance of the ribbons decreases dramatically after having been annealed at 460–580℃,and its reaction rate constant is less than 0.01 min–1.The main reason is the formation ofα-Fe precipitation phase in the ribbons after having been annealed at high temperatures and the destruction of the substable amorphous structure.These reduce the rate of hydroxyl radical formation.In contrast,the catalytic degradation performance of the 650–700℃annealed ribbons increases significantly,which increases to 3.77 times the degradation rate of the as-cast ribbons.The decolorization rate of acid orange 7 by the annealed ribbons reaches 99.22%within 15 min,which is 1.12 times that of the as-cast ribbons.The improvement of the catalytic degradation performance is attributed to the primary cell effect between the crystalline phase and the metal compounds and the substitution reaction between the Cu-enriched clusters and zero-valent iron.In this study,the influence mechanism of annealing crystallization on the performance of Fe-Si-B-Cu-Nb industrial amorphous ribbons for degrading azo dyes is revealed,which provides theoretical and experimental support for using aged iron-based amorphous ribbons to purify printing and dyeing waste-water and achieve“purification of waste-water by using alloy waste”.