# 3D Printing of Fe27Al24Ni22Cu18Co9 High-Entropy Alloy Scaffold with Direct Ink Writing for the Degradation of Methyl Red Azo Dye

## TL;DR

A 3D-printed high-entropy alloy efficiently degrades methyl red azo dye in acidic conditions within 28 minutes.

## Contribution

A new 3D-printed HEA scaffold is developed for efficient azo dye degradation with a proposed surface mechanism.

## Key findings

- The HEA Fe27Al24Ni22Cu18Co9 was synthesized and 3D printed using direct ink writing.
- The alloy degraded methyl red azo dye with 99% efficiency in 28 minutes at 60°C and pH 1.50.
- HPLC analysis suggests the degradation mechanism involves cleavage of the azo bond.

## Abstract

Dyes are emerging pollutants that can be classified in
various
ways, with azo dyes being among the most persistent in water. These
dyes contain conjugated double bonds and azo groups (R–NN–R’),
making their degradation in water a significant challenge. In this
study, we demonstrate that a high-entropy alloy (HEA) with the composition
Fe27Al24Ni22Cu18Co9 can be synthesized using mechanical alloying and subsequently
3D printed using material-extrusion direct ink writing. X-ray diffraction,
transmission electron microscopy, and field emission scanning electron
microscopy confirmed the synthesis of a new HEA with a face-centered
cubic crystal structure after 40 h of mechanical alloying. The degradation
properties of the 3D-printed HEA were then investigated for the azo
dye known as methyl red, revealing its efficiency at 60 °C in
the presence of nitric acid (pH = 1.50), with a degradation time of
28 min and an efficiency of 99%. Moreover, according to the results
of high-performance liquid chromatography, we propose the degradation
mechanism occurring at the surface of the Fe27Al24Ni22Cu18Co9 HEA that effectively
degrades methyl red and leading to the cleavage of the azo bond and
generating two different products.