Recovery of Tin as Tin oxide nanoparticles from waste printed circuit boards for photocatalytic dye degradation

Abstract

A simple eco-friendly process is proposed to retrieve tin from waste printed circuit boards (WPCBs) as tin oxide nanostructured powders. The WPCBs were leached in disodium salt of ethylene diamine tetraacetic acid (Na2-EDTA) chelating agent comparing results with acid leaching. Parameters affecting the leaching process such as sample particle size, pH, temperature, time, liquid/solid ratio, and concentration of Na2-EDTA were investigated. A 100% of Sn can be recovered by leaching in 0.1 mol/L Na2-EDTA solution for 3 hours at 80 °C with optimum conditions of pH: 5, liquid/solid ratio: 30, particle size −0.07 mm, and constant stirring of 400 rpm. Kinetic data suggest a diffusion-controlled process as the rate-determining step for the Na2-EDTA extraction of tin from WPCBs with an activation energy of 15.28 KJ·mol−1. Selective precipitation of Sn as tin oxide (SnO2) nanoparticles (NPs) from leachant solution was performed via a simple route using sodium hydroxide. Characterization tests (XRD, FTIR, EDX, FE-SEM, and TEM) were made to confirm the morphology of the nanoparticles. The prepared SnO2 NPs, having a size range of 8–12 nm, showed an excellent photocatalytic action towards methylene blue (MB) dye under ultraviolet (UV) light illumination with 90% efficiency after 180 min and showed good reusability after five consecutive cycles.