A Greener Chemistry Process Using Microwaves in Continuous Flow to Synthesize Metallic Bismuth Nanoparticles

Abstract

To address environmental concerns, improving synthesis processes in the nanoparticle field was a major challenge. Several processes of bismuth nanoparticle synthesis have been proposed in the past 10 years, but none of them have answered to all green chemistry principles suitable for nanomaterials. In this work, two syntheses of bismuth nanoparticles involving conventional thermal heating and microwave irradiation were compared in batch. All parameters have been studied to optimize the size and distribution of metallic bismuth nanoparticles. The choice of precursor, reducing agent, coating agent, solvents, the evaluation of quantities and the follow-up of reduction step, never documented before, have been fully described in this work. Following this optimization, the validation of synthesis reproducibility confirmed that microwave irradiation was the best process for obtaining bismuth nanoparticles according to green chemistry criteria. This study was continued using a millifluidic process to increase productivity. This continuous flow synthesis under microwave irradiation responded to industrial challenges and provided access to monodisperse bismuth nanoparticles that were characterized by several techniques.