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

Abstract

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, this paper investigates 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. It is found that the catalytic degradation performance of the ribbons after annealing at 460-580 ℃ decreases dramatically, and its reaction rate constant is less than 0.01 min<sup>-1</sup>. The main reason is the formation of ɑ-Fe precipitation phase in the ribbons after annealing 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 increased significantly, which increased to 3.77 times the degradation rate of the as-cast ribbons. The decolorization of the acid orange 7 at 15 min by the annealed ribbons reached 99.22 %, which was 1.12 times higher than that of the as-cast ribbons. The improvement of the catalytic degradation performance was 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. This study reveals the mechanism of crystallization on the performance of Fe-Si-B-Cu-Nb industrial amorphous ribbons for degrading azo dyes, which provides theoretical and experimental support for the use of aged iron-based amorphous ribbons to cleanse printing and dyeing waste-water to realize the "Using alloy wastes for refreshing waste-water".