An integrated DFT calculation and adsorption study of desiccated coconut waste-based biochar in CO 2 environment

This study presents a new series of amine-functionalized biochar derived from desiccated coconut waste (amine-biochar@DCW) as potential CO 2 adsorbents. The CO 2 adsorption experiment revealed that TETA-biochar@DCW had the highest adsorption capacity of 61.78 mg/g. Prior to the experimental studies, Density Functional Theory (DFT) was conducted at B3LYP/6-31G (d,p) to evaluate the energy band gap, global chemical reactivity descriptors (GCRD), and molecular electrostatic potentials (MEP) to compare the experimental findings. The results from the simulated data indicate that TETA-biochar@DCW has the lowest HOMO–LUMO gap at 2.7890 eV before adsorption, and it increases after CO 2 adsorption occurs. The 3D plots from MEP also show that TETA-biochar@DCW is a reactive adsorbent for CO 2 gases. Overall, the theoretical and experimental results of the amine-biochar@DCW suggest its potential as a promising and cost-effective adsorbent for CO 2 capture. Highlights • Newly prepared amine-biochar@DCW was assessed as CO 2 adsorbents. • TETA-biochar@DCW presents the highest CO 2 capture capacity. • TETA substituents significantly reduce the HOMO-LUMO gap values. • 3D MEP plots confirm the adsorption ability of TETA-biochar@DCW towards CO 2 gases. Graphical Abstract