Enhanced Photocatalytic and Biological Activities with the Effect of Magnesium-Substituted Aluminum Nanochromites, Synthesized by Citrate Gel Autocombustion Method

Abstract

Al_{1 – x}Mg_xCr₂O₄ nanochromites, where x = 0, 0.02, 0.04, 0.06, 0.08, and 0.10, were synthesized by citrate gel auto combustion technique. The X-ray diffraction study confirms the synthesized nanochromites belong to the spinel structure with the FD₃M space group, and the average crystallite size was 20 to 24 nm, which was calculated from the Debye–Scherrer formula. The distribution of these sizes would be seen in the SEM pictures, providing light on the uniformity. About 550 and 625 cm^–1 wavenumber domain FTIR bands are present in the FTIR spectrum, which correlate to the metal-oxygen bonds stretching vibrations of the octahedral (Mg–O bond linkage) and tetrahedral (Cr–O or Al–O bond linkage) sites. Using Tauc plots, the bandgap energy of the material was calculated, i.e., in between 2.21–3.26 eV. Fluorescence (FL) emission in the 400 nm region was seen in the PL spectra. Two organic industrial pollutants, such as Methylene Blue (MB) and Acid Red 18 (AR18), were utilized to examine the photocatalytic activity under visible light. Anticancer activity of Al_{1 – x}Mg_xCr₂O₄ nanochromites tested with HeLa CCL2 cells. Antibacterial activity is carried out by two gram-positive and two gram-negative bacterial agents, namely Staphylococcus aureus (ATCC6538), Bacillus subtilis (ATCC11774), Escherichia coli (ATCC8739), and Klebsiella pneumoniae (ATCC10031). Antifungal activity is investigated by two fungal pathogens (candida albicans (ATCC10231) and Aspergillus niger (ATCC1015)) by a pour plate method.