2. Materials and methods
With an aim to recover carbon from a range of motherboards, a number of random fragments of waste PCBs were used during the heat treatment runs. A schematic diagram of the experimental arrangement is shown in Fig. 1. Waste polymer rich PCB fragments were manually cut to a size of ~ 1 cm2 from a range of computer motherboards. Small pieces were weighed (~ 2 gm), placed in an alumina crucible and pushed into the cold zone (250 °C– 350 °C) of a high temperature horizontal tube furnace. The reaction assembly was held there for 5 min to avoid thermal shock, and then pushed into the hot zone, maintained at temperatures ranging from 750 °C to 1550 °C. The furnace was continuously purged with high purity argon gas at the rate of 1 L/min. The heat treatment was carried out for time periods ranging between 10 and 30 min. Representative results for 20 min are presented in this article. The specimens were pulled back into the cold zone and kept there for 15 min to avoid thermal cracking and the re-oxidation of residual products. All experiments were repeated several times to ascertain the reproducibility of results.