(592f) Effect of Fundamental Biopolymers in the Development of Surface Porosity and CO2 capture Capacity of Superactivated Hydrochars

Recently, hydrothermal carbonization (HTC) of biomass has been extensively studied to derive surface functionality rich hydrochar that can be chemically activated (CAC) to create porous superactivated hydrochars (SAH) for gas storage applications like carbon dioxide capture. However, despite identical thermochemical conversion (HTC and CAC) conditions, the SAHs derived from different biomass precursors exhibit dissimilarity in surface morphology as well as its corresponding gas storage capacity. Henceforth, finding the fundamental key underlying this discrepancy was of particular interest and motivated this study. For example, food-waste and loblolly-pine-derived SAHs carbonized at 220°C and activated at 800°C demonstrated BET surface area of 2885 and 1531 m²/g respectively. The distinct disparity in surface area puts special emphasis in rather revealing the potency of individual biopolymer constituents of a biomass in the process of favorable pore evolution that eventually affects CO₂ captured. Therefore, this study was designed to explore the biopolymer model compounds of cellulose, hemicellulose, lignin which were independently hydrothermally carbonized at 260°C and then activated using KOH to synthesize SAHs at temperatures using KOH: hydrochar ratio of 2:1 and 4:1. Furthermore, the synergistic effect of the biopolymers were also evaluated by proportionately formulating into simulated loblolly pine which also underwent HTC and CAC at aforementioned process conditions. All SAHs were characterized by N₂ adsorption–desorption, scanning electron microscopy, X-ray powder diffraction, proximate and ultimate analysis. Eventually, the applicability of the SAHs were explored by capturing CO₂ at ambient condition using High Pressure Volumetric Analyzer. The conclusion from our study could serve as the preliminary basis of establishing role of various fundamental biopolymers in pore evolution and hence preparation of high-performance biomass-based CO₂ storage medium.