ZnO/CuO nanocomposites from recycled printed circuit board: preparation and photocatalytic properties.

Cost-effective recycling of e-waste (from computer printed circuit boards, PCB's) for the synthesis of metal oxide nanocomposites is demonstrated. Metals in electronic components of waste memory slots were leached out using nitric acid (HNO3). Compositional analyses of the filtrate obtained after leaching were 66 wt.% Cu, 27.7 wt.% Zn, and 6.2 wt.% Ni. The leached out metal salt solutions were subjected to alkaline hydrothermal treatment to synthesize nanocomposites. Two nanoparticle samples were prepared, one without any stabilizing agent and another sample with PVP as a stabilizing agent. XRD, HR-XRD, HR-TEM, UV-DRS, UV-visible spectroscopy was used to characterize the as-prepared metal oxide nanoparticles. The analysis showed the formation of ZnO/CuO nanocomposites only. No nickel oxide component was precipitated under the studied hydrothermal experimental conditions. Most of the ZnO/CuO nanocomposite particles obtained by this route consisted of fine ZnO nanostructures precipitated on CuO cores. The ZnO and CuO components exhibit both direct and indirect band gaps in the visible range. The nanocomposites demonstrate good visible light photo-Fenton methyl orange (MO) degradation by pseudo-zero order kinetics.