Green Synthesis of Copper-Based Nanomaterials Using Pleurotus ostreatus: Process Optimization and Multi-technique Characterization
P. S. Akshaya
Department of Plant Pathology, College of Agriculture, Vellayani, India.
G. Heera *
Department of Plant Pathology, College of Agriculture, Vellayani, India.
P. J. Krishnapriya
Farming System Research Station, Sadanandapuram, India.
G. S. Sreekala
Department of Plantation, Spices, Medicinal and Aromatic Crops, College of Agriculture, Vellayani, India.
N. V. Radhakrishnan
Department of Plant Pathology, College of Agriculture, Vellayani, India.
*Author to whom correspondence should be addressed.
Abstract
Green synthesis provides a biological route for preparing copper-based materials. This study assessed reaction conditions for producing copper-based nanomaterials from fresh Pleurotus ostreatus fruiting-body extract and characterised the recovered material using complementary physicochemical techniques. A one-factor-at-a-time approach examined extract concentration, reaction pH, temperature and duration. Visual changes and UV–visible absorption were used to select conditions for subsequent preparation. An extract concentration of 15% (w/v), 5 mM CuSO₄, pH 8.5, 70 °C and 180 min were selected on the basis of optical response and physical appearance. UV–visible spectra showed a prominent absorption feature at 200–220 nm, together with secondary features that varied across reaction conditions. X-ray diffraction produced a broad pattern without clearly resolved characteristic peaks attributable to crystalline copper phases. Fourier-transform infrared spectra showed bands at 3242.87, 1606.93, 1025.42 and 611.85 cm⁻¹, indicating functional groups potentially associated with mushroom-derived biomolecules. Field-emission scanning electron microscopy showed irregular, aggregated nanoscale particles with a reported mean size of 38.7 nm. Energy-dispersive X-ray spectroscopy detected copper (3.6 wt%) alongside substantial carbon, nitrogen and oxygen signals. The measured zeta potential (−7.2 ± 2.1 mV) suggested limited electrostatic stabilisation. These findings provide a preliminary synthesis protocol and characterise a copper-containing material associated with organic constituents of the mushroom extract, while leaving its copper phase and oxidation state unresolved.
Keywords: Oyster mushroom, nanoparticles, UV–visible spectroscopy, physicochemical characterization, FTIR, X-ray diffraction, FE-SEM, EDS, zeta potential