Characterizations of High Entropy Alloy Powder as Catalyst Synthesized by Mechanical Alloying for Azo Dye Degradation

Abstract

FeCoNiAlSi and FeCoNiAlBSi high entropy alloys (HEAs) were synthesized by mechanical alloying. Phase evolution, crystallite size, lattice strain, microstructure and morphology for the two alloys were investigated. It was found that two simple structures which are face-centred cubic (FCC) and body-centered cubic (BCC/B2) solid solution appear in FeCoNiAlSi HEA after 50 h of milling. Formation of Fe2B peak was observed in the XRD pattern when a small amount of boron was added to the base alloys. The particle size of the alloy was increased after 20 h of milling time. The structural analysis shows that the average crystallite size decreases while lattice grain size increases with the increasing milling time. The morphology structure of the milled powders shows the particles size becomes rounded, flat and rough as the milling time prolongs. The newly developed HEA synthesized by mechanical alloying is expected to provide prominent efficiency in degradation of azo dyes (Methyl Orange). Although the HEAs have been reported to provide larger surface area and excellent capacity, only a few studies have been reported on degradation of azo dye by using HEAs as catalyst. Therefore, the method derived from the results of this study will contribute in treating azo dyes for wastewater treatment. Keywords: azo dye; high entropy alloys; mechanical alloying; crystal structure; morphology