Development of high entropy alloy (HEA) for Azo dye (methyl orange) degradation [EMBARGOED]

Abstract

The Fenton process is one of the chemical oxidation degradation processes widely used in wastewater management due to being environmentally safe. It involves a reaction in which iron-catalyzed hydrogen generates a hydroxyl radical. Even though the Fenton process can degrade the azo dye (methyl orange) solution, there are still substantial limitations, such as high sludge production due to high iron and limited catalytic activity. Therefore, this study focuses on improving the azo dye (methyl orange) degradation process in the Fenton process. A novel alloy known as FeCoNi(BxAl1-x) Si0.1 High Entropy Alloy (HEA) powders with different compositions was proposed as a catalytic material for the Fenton process. Mechanical alloying was used to produce HEA powder, which is expected to considerably improve its efficiency in the degradation of azo dye (methyl orange). The characteristics of the milled HEA powder, as well as its degradation efficiency and kinetic mechanism in the Fenton process, were investigated. FeCoNi(BxAl1-x) 0.1Si0.1 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) powders were milled in high purity argon atmospheres for various times from 5H to 160H. The result shows milled HEA powders were diffused completely into solid solution when three phases were appeared after 160H of milling which are FCC, Fe2B and BCC/B2. The particle size reduced as the milling time increased and the particle distribution became more homogenous at 160H. The reduction of particle sizes increased the surface area, thus providing more catalytic sites for HEA. From the Fenton process, the optimum molar ratio (?[Fe?^(2+)]/[H_2 O_2]) of Fenton reagents was 10:1.02. The kinetic mechanism of milled HEA powder as catalyst in the Fenton process was determined by the pseudo-first order and pseudo-second order. The highest k (decolorization rate constant) value of the HEA catalyst occurred at 30 minutes within 60 minutes of the Fenton reaction. The results showed the feasibility and efficiency of the HEA as catalytic materials in the Fenton process. Therefore, this research can contribute to the development of an appealing, low-cost, and efficient approach for HEA functional applications in wastewater management.