Direct transformation of waste printed circuit boards into high surface area t-SnO₂ for photocatalytic dye degradation

One of the most challenging issues the world has faced is what to do with discarded electronic devices or electronic waste (e-waste). Direct transformation of e-wastes to value-added materials helps to conserve resources and at the same time prevents the environmental impacts of conventional disposal. In this study, a spent solution from e-waste processing directly was transformed into high surface area t-SnO₂ nano-particles (NPs). We show how t-SnO₂ NPs are formed as unexpected spontaneous precipitation with a very slow kinetic rate from an impregnated e-waste solution in the absence of any additives. This research showed that conducting a precipitation process on equilibrium lines can generate high-quality NPs. The mechanism of the process and the characteristics (phase and size) of the NPs were analyzed using HR-TEM, BET, HR-XPS, FTIR, TGA-DTG, and HR-XRD (using Rietveld refinement). The NPs provides a very high surface area of 241 m²/g and each NP (≈3.9 nm) contains two crystallites (≈2.6 nm), which shows that these NPs can be considered as quantum dots (QDs). Finally, the produced NPs successfully removed dye pollutants from simulated industrial wastewater. In this way, one waste material was used to remove another.