Effective adsorption of dysprosium ions on amino and carboxyl functionalized mesoporous silica sheets

Abstract

Securing a stable supply of dysprosium (Dy) is one of the major problems facing the automotive industry due to increased Dy consumption and low-volume production. Investigations of new recycling methods are therefore extremely important. In this study, we focused on mesoporous silica particles (MPS) with tunable nanoscale mesopores (2–50 nm), large surface areas, high pore volumes, and abundant surface chemistry. To perform adsorption experiments with several metal ions in the solution, the silica materials were treated via amino functionalization using silane coupling reagents, 3-aminopropyltriethoxysilane (APTES), N-(2-aminoethyl)-3-aminopropyltriethoxysilane (N2APTES), and N-(6-aminohexyl)-3-aminopropyltrimethoxysilane (N6APTES), as well as via carboxyl functionalization using diglycolic acid. Interestingly, MPS sheet-2HNHCOOH, a product with a sheet-like morphology, exhibited enhanced Dy ion adsorption (13.3 µg/mg). The sheets retained approximately100% in the initial capacity after 10 cycles. The results suggest that MPS sheet-2HNHCOOH is an appropriate a candidate material for selective Dy ion adsorption.