Recycling Polymer-Rich Waste Printed Circuit Boards at High Temperatures: Recovery of Value-Added Carbon Resources

Abstract

High-temperature transformation studies were carried out on polymer-rich waste printed circuit boards (PCBs) in the temperature range of 750–1,350 °C in argon atmosphere. Copper-rich metallic fractions started to separate out as foils/droplets at temperatures above 950 °C producing significant quantities of carbonaceous residue. In-depth characterisation of the residue was carried out using X-ray diffraction, Raman spectroscopy, SEM/EDS, surface area analysis, and LECO measurements. The recovery of carbons from waste PCBs reached up to 25 % of total weight. These carbons generally had a disordered structure with 3–4 layers stacking along the c-axis. The presence of metals in the carbonaceous residue became negligibly small at 1,350 °C, significantly enhancing the quality of the carbonaceous product (carbon content: 52–74 wt%). This study has shown that potentially vast reserves of carbon could be recovered from e-waste through appropriate recycling, while minimising the impact of waste on the environment.