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

Abstract

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.