Bio-fabrication of cobalt oxide nanoparticles using walnut shell extract: antibacterial, antioxidant, and photocatalytic potential

Abstract

Researchers have focussed on using cobalt oxide nanoparticles (CoONPs) as anti-cancerous, antimicrobial agents, and other pharmacological activities. This work explores the environmentally friendly synthesis of cobalt oxide nanoparticles (CoONPs) utilizing walnut shell extract, which has a high phenolic content and is a natural reducing agent. After cobalt chloride is reduced during the synthesis process, nanoparticles are produced. These were then characterized by several methods, such as UV–visible absorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR). The SEM examination disclosed the CoONPs’ spherical shape, and XRD validated their crystalline structure with particle sizes ranging from 10 to 45 nm. The antibacterial properties of the synthesized CoONPs were evaluated against several pathogenic bacteria, including Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Streptococcus pneumoniae. The results demonstrated significant antibacterial activity, with inhibition zones comparable to the standard antibiotic vancomycin, highlighting the potential of CoONPs as effective antimicrobial agents in combating antibiotic resistance. Furthermore, the antioxidant activity was assessed using the DPPH scavenging assay, which indicated a concentration-dependent increase in activity, reaching 91.52% at 100 µg/ml. Apart from their biological uses, the degradation of Congo red dye under UV and sunlight exposure was used to investigate the photocatalytic potential of CoONPs. The study discovered that the nanoparticles efficiently aided in the process of disintegration, indicating their potential use in environmental remediation. Overall, this study highlights the multifunctional qualities of CoONPs and advances our understanding of their synthesis and characterization, opening the door for potential uses in environmental science and medicine in the future.

Graphical abstract