Cocoa shell-deriving hydrochar modified through aminosilane grafting and cobalt particle dispersion as potential carbon dioxide adsorbent

Abstract

This work was achieved to investigate the effect of both aminopropyltriethoxysilane (APTES) grafting and cobalt particle incorporation on the CO2 adsorption behavior of cocoa shell based hydrochar (HC). Electron microscopy and measurements using nitrogen adsorption-desorption isotherms showed a structure swelling after APTES grafting, followed by a compaction after Co particle insertion that attenuates the surface basicity. HC-APTES-Co displayed higher CO2 retention capacity than its metal-free counterpart, in spite of its lower basicity and porosity. CO2 adsorption was found to obey pseudo-first order kinetics and intra-particle diffusion mechanisms due to the predominance of physical interaction. This favors CO2 condensation of higher CO2 amount than predicted by the stoichiometry of carbamate formation. This concept allows envisaging promising prospects for plant-deriving adsorbents intended for CO2 concentration and valorization into added values products.