Size-controlled preparation of Cu2O nanoparticles from waste printed circuit boards by supercritical water combined with electrokinetic process.

In this work, an effective and size-controlled process for preparing Cu(2)O nanomaterials from waste PCBs by supercritical water (SCW) combined with electrokinetic (EK) technique was developed. SCW was used for the pretreatment of waste PCBs, and highly uniform and monodisperse Cu(2)O nanoparticles with different sizes were prepared successfully from waste PCBs in EK process. Cu(2)O nanoparticles with average sizes of 5, 11, 25 and 40 nm could be prepared in the presence of nanoparticles stabilizer (PVP) with the concentrations of 40, 30, 20 and 10 g/L, respectively. The average size of Cu(2)O nanoparticles decreased from 49.5 to 18.2 nm when current density increased from 10 to 20 mA/cm(2), and the size uniformity of nanoparticles was improved distinctly at a higher current density. The size of Cu(2)O nanoparticles increased with the increase of EK time, and agglomeration of particles was observed after 8h EK reaction. Up to 90 wt% of the Cu in waste PCBs could be recovered as Cu(2)O nanoparticles under optimized condition. It is believed that the process developed in this study is simple and practical for size-controlled preparation of nanomaterials from waste PCBs or other Cu-rich solid wastes.