Hydrometallurgical recovery of α-Fe₂O₃ from red mud and photo-Fenton degradation of organic dye using CuO promoted α-Fe₂O₃

ABSTRACT

The ecological balance is disturbed by the massive generation of solid waste (red mud) from aluminum industries. It contained various types of metal oxides with different proportions, and it is essential to extract these valuable metals to maintain sustainability. The hydrometallurgical route is applied to extract hematite (α-Fe₂O₃) from red mud. This route involves leaching, solvent extraction, and precipitation. The α-Fe₂O₃ is mixed with different weight percentages of CuO to form a heterostructure (CuO/α-Fe₂O₃). The malachite green (MG) is degraded using the α-Fe₂O₃-CuO catalyst for photo-Fenton reaction. All the composites are characterised by XRD, FTIR, UV-vis DRS, PL, and electrochemical study. XRD figure confirmed that hematite (α-Fe₂O₃) is extracted successfully from red mud, and goethite (α-FeOOH) is suppressed. The reducibility nature of CuO, created a synergism between α-Fe₂O₃ and CuO, which leads to suppression of e⁻/h⁺ recombination by proper charge transfer. It is confirmed through PL spectra and electrochemical study (Nyquist plot). 20CuO/α-Fe₂O₃ showed the maximum degradation (98%) of malachite green (MG).

GRAPHICAL ABSTRACT

KEYWORDS:

• Red mud
• leaching
• extraction
• composite
• photocatalysis

Acknowledgment

The authors are thankful to Prof. Manoj Ranjan Nayak, President Siksha ‘O’ Anusandhan University, for his support to carry out the research work.

Disclosure statement

No potential conflict of interest was reported by the author(s).