Waste‐Fish‐Derived Nitrogen Self‐Doped Microporous Carbon as Effective Sorbent for CO2 Capture

Protein‐rich waste fish was used to produce nitrogen self‐doped microporous carbon by KOH activation and studied for CO2 adsorption application. The effect of a pre‐carbonization process of dried fish powder on the textural properties and yield of fish protein derived carbon (FPDC) was also investigated. The textural properties of FPDC‐x–y were further optimized by varying KOH to Fish powder weight ratios (x) and activation temperatures (y). Activated carbons with high specific surface area and pore volume were obtained using mild activation conditions (x= 0.5 to 1.5, y= 550 to 650 °C). The nitrogen content (3.79 to 12.43 wt%) and carbon yield (2.3 to15 wt%) depended strongly on the KOH to Fish powder weight ratio and activation temperature. Highest surface area (2565 m2 g−1) and total pore volume (1.32 cm3 g−1) were exhibited by FPDC‐1‐650 whereas FPDC‐1‐550 exhibited the highest micropore volume (0.33 cm3 g−1). The synergistic effect of microporosity and nitrogen functionality had a positive influence on CO2 uptake in the FPDC. The FPDC‐0.5‐600 shows a maximum CO2 adsorption capacity of 4.03 and 6.07 mmol g−1 at 25 and 0 oC, respectively, at 1 bar. CO2 adsorption on FPDC‐x–y shows excellent recyclability and CO2/N2 selectivity in the range of 23 to 47 at 0 oC. N‐doped activated carbon (AC) was prepared from protein‐rich wasted fish using KOH as activating agent and studied for CO2 adsorption application. Use of mild activation conditions resulted in high in situ nitrogen‐doping and high microporosity in the activated carbon which was favorable for high CO2 uptake. The AC showed excellent recyclability and good selectivity of CO2 over N2.