Biosynthesis of Manganese Dioxide Nanoparticles and Optimization of Reaction Variables

Abstract

Biosynthesis is an efficient and environmentally friendly process used to synthesize nanoparticles. This study presents a simple, environmentally friendly, and cost-effective method for synthesizing manganese dioxide nanoparticles from aqueous manganese (II) acetate using lemon extract as a reducing agent. Turmeric extract (curcumin) was employed to stabilize the biosynthesized nanoparticles. UV-visible spectroscopy was used to evaluate the concentration of nanoparticles at 350 nm wavelength. The scanning electron microscope verified that the nanoparticles had a rod-like shape. Fourier's transform infrared spectroscopy revealed an absorption peak at 558 cm-1, which corresponded to the stretching vibration of O-Mn-O. Response surface methodology, namely the central composite design, was employed to optimize reaction variables such as temperature, pH, and lemon extract ratio during the synthesis. These variables were optimized by measuring the absorption intensity of nanoparticles at 350 nm with UV-visible spectroscopy. The optimal values were claimed to be a lemon extract ratio of 75%, a temperature of 50°C, and a pH of 3.4. The lemon extract ratio was found to be a viable variable that determines the formation of nanoparticles, followed by temperature and pH. Hence, the utilization of sustainable plant extracts enhances the synthesis of nanoparticles without actual effects on the environment. MnO2 nanoparticles are used in a variety of applications, including energy storage, photocatalysis, adsorbents, sensors, and detectors for a wide range of biomedical molecules.