Green synthesized CaO nanoparticles using various mushroom species extracts: Structural characterization, antioxidant and photodegradation ability

In this work, calcium oxide nanoparticles (CaO-NPs) were first green synthesized employing aqueous extracts of four mushroom species. Thermogravimetric analysis (TGA) revealed that the optimum calcination temperature for production of CaO-NPs was 700 °C. Phytochemical screening of mushroom extracts indicated the presence of organic components that could mediate CaO-NP production. The structural and optical properties of the obtained samples were investigated using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction analysis (XRD), UV–visible spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Also, the antioxidant capabilities of aqueous extracts and CaO-NPs were evaluated. Results showed that depending on the species of mushroom extract used, three distinct NP morphologies, plate-like, spheroidal, and chain-like, were observed. CaO-NPs presented band gaps ranging from 5.29 to 5.34 eV. Using aqueous extracts from V. volvacea resulted in smaller particle-sized CaO-NPs (18.02 ± 0.33 nm). These CaO-NPs showed higher antioxidant activities than other CaO-NP samples, which was correlated with the extract's higher antioxidant activity. Selected photocatalytic activities of CaO-NPs synthesized from an aqueous extract of V. volvacea were also studied. The results showed a degraded efficiency, estimated to be 30 % in 120 min. • CaO-NPs were synthesized employing an aqueous extract of four mushroom species. • Three different morphologies of nanoparticles were found. CaO-NPs ranged in size from 18.02 ± 0.33 to 64.07 ± 1.56 nm. • V. volvacea extracts showed higher antioxidant activity and smaller particle sizes. Degradation efficiency of CaO-NPs estimated to be 30% in 120 min.