CO2 Capture Using Nitrogen-Doped Porous Carbons Derived from Waste Printed Circuit Boards

We introduce a novel procedure to synthesize a novel CO2 adsorbent from waste printed circuit boards. This innovative technique enables the production of nitrogen-rich porous carbon adsorbents at low activation temperatures, ranging from 400 to 500°C, compared to traditional processes that require activation temperatures exceeding 600°C when using KOH. By fine-tuning the activation temperature and modifying the proportion of reactants, namely, NaNH2, to nonmetallic fractions, it is possible to customize both the pore architecture and the nitrogen levels in the adsorbent, thereby improving its CO2 adsorption efficiency. The adsorbent, denoted as EN-450-2 (epoxy nitrogen-doped adsorbent activated at 450°C with a weight ratio of 2:1 NaNH2:electronic waste nonmetal fraction), exhibits a remarkable surface area of 2270 m2/g. It demonstrates a CO2 adsorption capacity of 5.17 mmol/g at 0°C and 1 bar and 3.14 mmol/g at 25°C and 1 bar. Comprehensive analysis indicates that a combination of factors such as pore structure (i.e., narrow micropore, surface area, and total pore volume) influences the CO2 adsorption performance. At 1 bar pressure and 25°C, EN-450-2 exhibits exceptional CO2/N2 selectivity, moderate isosteric heat of adsorption, rapid adsorption kinetics, substantial dynamic CO2 capture capacity, and enduring regeneration over five cycles. This work not only provides a sustainable solution to e-waste management but also contributes to global efforts in combating climate change through improved CO2 capture.