Abstract:
The increase in environmental pollution due to synthetic dye effluents and pathogenic
bacteria has resulted in a serious problem for human health and the environment. So it is
essential to use environmentally benign and simple methods for removing organic
contaminants and water disinfection. The main objective of this study was to synthesize
Fe2O3 NPs and Ag/Fe2O3 NCs using Carica papaya peel extract for photocatalytic,
antioxidant, and antibacterial applications. Synthesis parameters such as concentration of
precursor, pH of the reaction medium, papaya peel extract volume, reaction time, and
temperature that affect the yield and the properties of NPs were optimized. The resulting NPs
and NCs were analysed using UV-Vis, XRD, FT-IR, and SEM. The synthesized Fe2O3 NPs
and Ag/Fe2O3 NCs exhibited a UV-Vis absorption band at 296 nm and 347 nm with bandgap
of 3.34 eV and 2.91 eV, respectively. The XRD data revealed that the average crystalline size
of Fe2O3 NPs and Ag/Fe2O3 NCs was 26.72 nm and 29.17 nm, respectively. The
photocatalytic performance of Ag/Fe2O3 NCs towards the degradation of MB dye was
evaluated. Degradation efficiency for Ag/Fe2O3 NCs was calculated to be 92.97%, which is
higher than that of Fe2O3 (72%), indicating the photocatalytic activity is improved after
decorating Ag onto the Fe2O3 NPs. The antibacterial test showed that Ag/Fe2O3 NCs has a
wide range of antibacterial activities against Gram-positive bacteria (S. aureus and B. cereus)
and Gram-negative bacteria (E. coli and S.typhi). The zone of inhibition for Ag/ Fe2O3 NCs
against B. cereus, S. aureus, S. typhi, and E. coli is estimated to be 19.5 mm, 19 mm, 18 mm,
and 16.2 mm, respectively. The antioxidant activity of the synthesized nanomaterial was
conducted using DPPH (2, 2-diphenyl-1 picrylhydrazyl) scavenging assay, and the IC50
values for antioxidant activity of Ag/Fe2O3 NCs was calculated to be 15.38 μg/mL. The
results illustrated in this paper imply that the multifunctional performances such as efficient
photocatalytic degradation of MB dye, superior antibacterial and antioxidant activities that
make the synthesized Ag/Fe2O3 NCs a promising photocatalyst for dye-polluted water and
disinfectant agent for wastewater treatment and purification and antioxidant agent for radical
scavenging activity.
