Microwave-assisted green synthesis of selenium nanoparticles using citrus extracts: Insights into size-controlled formation and surface characteristics

This study presents a novel, eco-friendly microwave-assisted method for the synthesis of selenium nanoparticles (SeNPs), employing orange and lime juices and peel extracts as natural reducing and stabilizing agents. This rapid, solvent-free technique utilizes cost-effective, biodegradable raw materials, facilitating synthesis in a matter of minutes while reducing energy consumption, aligning with the principles of green chemistry. Microwave energy facilitates the efficient and size-controlled SeNP formation, thereby contributing to sustainability and resource optimization. A comprehensive investigation was conducted to evaluate the influence of key synthesis parameters, including Se precursor concentration (80 - 400 mg L -1 ), extract type and quantity (10 - 50% v/v), reaction time (10 - 20 min), and microwave power (90 – 180 W). This approach enabled control over NP size (70 - 250 nm). It has been demonstrated that the chemical nature of the biomolecules and microwave irradiation significantly affect the nucleation and growth rates of SeNPs. The analysis, conducted using HPLC-ESI-MS/MS, revealed that extracts of the peel, rich in caffeic acid, provide more robust reducing conditions than juices, influencing synthesis mechanisms of SeNPs. A multifunctional organic network surrounding the NPs, has been shown to enhance their chemical activity, suggesting their potential for use in Cd(II) removal and environmental remediation efforts. • A cost-effective and fast microwave-assisted method for selenium nanoparticle production (SeNPs) using citrus juice and peel extract is presented • Reaction conditions can be tuned to produce spherical SeNPs with a wide range of sizes and particle number concentrations • Citrus peel extracts provide stronger reducing conditions compared to citrus juices, resulting in more effective nanoparticle formation • SeNPs synthesized using lime peel extract demonstrate the highest effciency in cadmium ions adsorption • Advanced spectrometric techniques provide reliable characterization of key physicochemical properties and elucidation of the synthesis mechanism