Toward environmentally favorable nano-sensing by production of reusable gold nanoparticles from gold nano-waste: life cycle and nanocircular economy implications

Abstract

The environmental impacts of gold nanoparticle (AuNP)-based sensing were investigated using a cradle-to-grave life cycle assessment (LCA). The LCA model considered AuNP synthesis, surface functionalization, an AuNP-based detection assay, and disposal. Additionally, the model incorporated two potential Au nano-waste reuse strategies reliant upon α-cyclodextrin (α-CD) or Triton X-114. The results show that, across ten midpoint categories that >80.4% of the environmental impacts arise from AuNP synthesis thus demonstrating the benefit of reuse of Au nano-wastes. Importantly, the two different reuse strategies enhance the environmental sustainability of the sensing application. Gold recovery contributed to a significant reduction in the amount of pristine Au³⁺ initially required despite the additional chemical and electrical demands of the reuse processes. Sensitivity analysis focused on two variables (i.e., recovery efficiency and the number of reuse cycles) indicated that the environmental favorability of the sensing application is dominated by recovery efficiency. Finally, the reuse of Au nano-waste reduces the energy demand of nano-sensing and the total cost of AuNP-based industries, thus illustrating energy and circular economy implications.