Green synthesis of copper nanoparticles with ultrasound assistance

A study of the synthesis of metallic copper (Cu) nanoparticles using ultrasound assistance and green reagents is presented. Copper recovered from the pretreatment of electronic circuit boards was used as the raw material in this study. Different process parameters, namely, the effect of ultrasound, reducing agents and capping agents, were investigated, where L-ascorbic acid and sodium borohydride were used as reducing agents. In order to make the process environmentally friendly, the synthesis was performed in aqueous solutions, in ambient conditions, and exposed to air. The nanoparticles were characterized with SEM, TEM, XRD, UV-spectroscopy, and by using laser diffraction particle size analyzer. Results show that, using L-ascorbic acid as reducing agents, the use of ultrasound leads to the production of Cu nanoparticles, with a reaction time of 10 min, compared with a time of several hours when performing the synthesis without ultrasound. The nanoparticles produced by this method have dimensions of approximately 5 nm and remain - stable in the solutions for days. Moreover, by using Cu nitrate from the leaching solution of electronic scraps, obtaining nanoparticles with high purity has been made possible.