Green Approach and Thermal Modification for Nanoparticles Development of Alumina and Its Phases Using Aluminium Waste Cans as a Precursor

Alumina and its phases in nanoparticle (NPs) form were synthesized from aluminium waste cans (AWC) through green and thermal treatment. Lemongrass (Cymbopogan citratus) extract was used as a green reducing agent to produce the alumina NPs which was calcined at a temperature range of 300–1100 °C for alumina NPs phase formations. The characterizations of each of the developed samples were investigated using X-ray fluorescence (XRF), X-ray diffraction (XRD), Density Function Theory (DFT) method, and Dynamic Light Scattering (DLS). The XRF result revealed that a pure 97.11% Al₂O₃ was produced from the AWC. The XRD showed good crystallinity of the Al₂O₃ (~ 41 nm) when lemongrass extract was used to reduce the particle size of the Al₂O₃ powder (~ 76 nm). The XRD also revealed the formation of γ, γ/δ, δ, θ, and α phases of alumina NPs from the Al₂O₃ NPs after calcination at a temperature of 300 °C, 500 °C. 700 °C, 900 °C, and 1100 °C respectively. The DFT showed an increase in the surface area (m²/g) from 36.71 to 84.31 as the calcination temperature increased. The DLS also confirmed that the increase in the calcination temperature reduces the particle size distribution of the Al₂O₃ NPs. Therefore, the AWC was successfully converted to pure Al₂O₃ NPs and alumina phases, which could replace off-the-shelf aluminium compounds for various industrial applications.