ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Enhanced CO₂ uptake of mesoporous activated carbon derived from chitosan/casein coacervate

K. Malini, D. Selvakumar, and N. S. Kumar

Defence Bioengineering and Electromedical Laboratory (DEBEL), DRDO, Bangalore, India

E-mail: dhanaselva@gmail.com

Received: 19 October 2022  Accepted: 4 March 2023

Abstract:

Preparation of nitrogen-doped porous activated carbon materials gained much importance in recent years due to their enhanced CO₂ adsorption properties and CO₂/N₂ selectivity as against undoped counterparts. In this study, N-doped activated carbon macrospheres were prepared by carbonization of casein-coated chitosan macrospheres obtained by coacervation method, where chitosan serves as a nitrogen containing carbon (C/N) precursor and casein serves as an additional polymeric nitrogen source. Uncoated chitosan macrospheres were also prepared in NaOH solution for comparative studies. SEM–EDS, CHN analysis, BET surface area analysis, Raman, FTIR, XRD and XPS were performed on both samples to compare the textural characteristics of the activated carbons prepared. Thermal analysis using TGA and DTG revealed that coacervated sample possessed improved thermal stability. The CO₂ adsorption studies showed an enhanced adsorption capacity for the activated carbon prepared from chitosan/casein macrospheres (123.57 mg/g) than for the activated carbon from chitosan/NaOH macrospheres (97.98 mg/g) at 25 °C and 1 bar. The activated carbon prepared from chitosan/casein macrospheres exhibited an excellent CO₂/N₂ selectivity. Furthermore, a steady CO₂ uptake studied up to 5 cycles indicates the material is thermally stable and reusable without deterioration in CO₂ adsorption capacity.

Graphical abstract

Keywords: Chitosan; Casein; Coacervate; Activated carbon; CO2 adsorption

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02768-6

Chemical Papers 77 (8) 4179–4192 (2023)