Recycling of waste glass fiber-reinforced plastics using pyrolysis with KOH

Abstract

Glass fiber-reinforced plastics (GFRPs) are composite materials with high strength and flame retardancy; however, their disposal process is expensive, causing illegal dumping. Herein, recycling of waste GFRPs using pyrolysis with KOH under an inert atmosphere was attempted by the gasification of resin and conversion of glass fibers into soluble silicate. The pyrolysis behavior of the GFRP, characteristics of the obtained residue, composition and yield of the generated gas, and extracted amount of silica in the solution obtained using KOH were investigated. The results indicated that the gasification of the resin and conversion of the glass fiber into soluble silicate were promoted by pyrolysis with KOH. With an increase in the heating temperature, KOH addition amount, and heating time, the yield of gases, especially flammable gases (H2 and CH4), and the extracted amount of silica increased, whereas the residual rate decreased. The amount of silica extracted using 1 M HCl is higher than that extracted using distilled water. Compared with those obtained using NaOH, the yield of gases and specific surface area of the residue achieved using KOH are superior, while the extracted amount of silica obtained using NaOH is higher than that acquired using KOH.