Obtaining Al-Cu-Fe particles with a Cu-rich skeletal surface for catalytical applications

Abstract

The expansion of the understanding horizon of quasicrystals relies, not only in its crystallographic and physical study, but also its applications. Following the last decades of investigation of different properties and possible applications of quasicrystals, this study used a quasicrystalline alloy powder of the Al-Fe-Cu system as catalyst for the degradation of the organic dye, Congo Red. The absence of studies that deeply evaluate these properties, alongside the pressing environmental issue of water pollutant control, make this material an alternative to perform the removal of these type of substances from industrial effluents. In this study, an Al62.5Cu25Fe12.5 (%at.) alloy was fabricated by gas-atomization, following a leaching procedure of the quasicrystal-based powder in an alkaline solution aiming to remove aluminium atoms from the surface, exposing the Cu-rich phase. The micro and nanometric Cu-rich particles are the ones responsible for the catalytic effect in theses reactions. The gas-atomized and leached powder were microstructurally characterized using several techniques. The Congo Red decomposition, due to the presence of the leached particles was monitored by Ultraviolet Spectroscopy. The results indicate that the Al62.5Cu25Fe12.5 microstructure, composed initially by icosahedral quasicrystals and the τ-AlCu(Fe) phases, developed a skeletal structure where most of the quasicrystals from the particle´s surface were removed while the τ -AlCu(Fe) phase was mostly preserved as it was found in the atomized particles. The presence of this phase at the particle´s surface, provided optimal locations for the Congo Red molecules to interact with the Cu rich phase.