New Porous Amine Functionalized Biochar based Desiccated Coconut Waste as Efficient CO2 Adsorbents

Abstract Environmental problems such as climate change and global warming caused by greenhouse gases, mainly CO2, have become a worldwide topic of concern. Adsorption is a promising method for CO2 capture. In this research, a series of amine functionalized on biochar based desiccated coconut waste (amine-biochar@DCW) namely ethylenediamine functionalized biochar@DCW (EDA-biochar@DCW), diethylenetriamine functionalized biochar@DCW (DETA-biochar@DCW), triethylenetetramine functionalized biochar@DCW (TETA-biochar@DCW), tetraethylenepentamine functionalized biochar@DCW (TEPA-biochar@DCW), and pentaethylenehexamine functionalized biochar@DCW (PEHA-biochar@DCW) adsorbents were synthesized and characterized. From the characterization analyses, series of amine-biochar@DCW adsorbents had better developed pore structure and larger specific surface area than that of pristine desiccated coconut waste (DCW). Furthermore, the results showed that the increase percentage of elemental of C and N as well the presence peaks NH stretching, NH bending, CN stretching, and CN bending, revealing the presence of amine on the surface of biochar@DCW. From the CO2 adsorption experiment, among amine modified biochar adsorbents, TETA-biochar@DCW had higher CO2 adsorption capacity (61.78 mg/g) with mass ratio (m:m) of biochar@DCW:TETA (1:2). The adsorption kinetics on the TETA-biochar@DCW was best fitted by the pseudo-second model, suggesting the adsorption process occurs through chemisorption. Additionally, TETA-biochar@DCW depicts high selectivity towards CO2 gas and good reusability after five CO2 adsorption–desorption cycles.