Green synthesis of pyrite nanoparticles: nanozyme activity and kinetic studies

This study was to present the green synthesis of pyrite nanoparticles (FeS₂-NPs) as a nanozyme using Acanthophyllum laxiusculum root extract. The synthesized FeS₂-NPs were characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). The operating parameters for the synthesis of FeS₂-NPs, including surfactant concentration, temperature, time, and sulfur concentration, were investigated. The obtained results revealed that the optimal conditions for the synthesis of FeS₂-NPs were 10 mL of the Acanthophyllum laxiusculum root extract as the surfactant, 200 °C temperature, and 2 moL sodium thiosulfate (Na₂S₂O₃) as an S source. The Acanthophyllum laxiusculum root extract had a significant effect on the morphology and particle size of FeS₂-NPs. Moreover, the obtained results demonstrated that the synthesized nanozymes could display their maximum peroxidase-like (POD-like) activity at the temperature of 25 °C and the pH of 4.0. The kinetic parameters, K_m and V_max, were subsequently determined for the synthesized nanozymes of FeS₂ as 0.041 mM and 11.38 × 10^–8 M/s, respectively. In addition, high nanozyme activity was observed in the presence of isopropyl alcohol (C₃H₈O) and 3, 3′,5,5′ tetramethylbenzidine (TMB). Therefore, the natural surfactant of Acanthophyllum laxiusculum root extract could be a high-potential and eco-friendly chemical for the synthesis of FeS₂-NPs.