Eco-friendly synthesis of CuO nanoparticles using Pulicaria gnaphalodes extract and biological and photocatalytic properties

The issue of obtaining clean water is a significant problem globally, and traditional methods for addressing it have various shortcomings. To tackle this problem, novel approaches and substances have been introduced to handle water purification. In this research, copper oxide nanoparticles (CuO NPs) were synthesized using Pulicaria gnaphalodes extract as stabilizing and capping agents. To verify the synthesis, various techniques such as EDS, FT-IR, TEM, XRD, and FESEM were employed. The XRD analysis revealed that a monoclinic structure of single-phase CuO was formed, and the EDS spectrum demonstrated the predominant presence of Cu and O elements without any contaminants. The desired chemical structure was confirmed by the FT-IR spectrum. Additionally, the TEM and FESEM images indicated that the size of the synthesized CuO nanoparticles was within the nanometer range. The antibacterial activity of the CuO NPs was investigated against Gram-positive and Gram-negative strains. The highest antibacterial activity was recorded against Staphylococcus aureus and Enterococcus faecalis bacteria with MIC value of 1.25 mg/mL. To determine the antioxidant property, the inhibition rate of free radicals of DPPH was evaluated. The CuO nanoparticles, when tested at a concentration of 1 mg/mL, exhibited an inhibition rate of 52.33% against DPPH free radicals. The photocatalytic efficacy of CuO NPs was evaluated for the degradation of humic acid (HA), and the key parameters were optimized. Under optimal conditions, including pH = 3, nanoparticles dose of 0.05 g/L, HA concentration of 10 mg/L, and a contact time of 120 min, the photocatalytic efficiency was improved to 75.23%. The findings of this research indicate that CuO nanoparticles have the potential to be a reliable antibacterial and antioxidant agent. Additionally, these nanoparticles can be used efficiently for decontaminating water bodies that have been polluted with harmful industrial dyes to decrease their toxicity.