Decomposition behavior and mechanism of epoxy resin from waste integrated circuits under supercritical water condition

Integrated circuits (IC), a kind of widely used electronic component, is paid great attention to recover valuable materials and remove hazardous materials after being discarded. However, refractory epoxy resin as packaging material is tightly covered on waste IC. It is difficult to remove epoxy resin and recover metals environmentally friendly by traditional methods. In this study, decomposition of epoxy resin from waste IC in supercritical water (SCW) was investigated. The epoxy resin could be efficiently decomposed under SCW condition. High temperature and long operation time of SCW treatment was positive for decomposition efficiency. The main decomposition intermediates and products were phenol and its derivatives. The decomposition mechanism of epoxy resin in supercritical water belongs to complex free radical reaction. Seven proposed pathways for the formation of key intermediates were investigated, with the kinetic and thermodynamic parameters obtained by density functional theory calculations. The analyzation provided assistance in the optimization of SCW treatment. Epoxy resin conversion rate could reach 95.51% under the condition of 500 ℃, 23 MPa and 90 min, then metals could be easily separated and recovered from solid residue. Thus, SCW treatment presents an efficient and green process for the recycle of waste IC.