| Abstrakt: |
With the growing rise in CO2 emission, resulting in accelerated global warming, there is an increased utilization of lignocellulosic waste biomass to synthesize inexpensive CO2 adsorbents, via hydrothermal carbonization (HTC) of biomass followed by chemical activation (CAC) to create porous activated hydrochar that can capture CO2. However, despite analogous thermochemical conversion (HTC and CAC) conditions, the activated hydrochars derived from different biomass precursors exhibit dissimilarity in surface morphology and its corresponding CO2 capture capacity. Hence, finding the fundamental key underlying this discrepancy is of interest where biopolymer constituents' composition is hypothesized to be the determining factor. This study, therefore, explored the biopolymer model compounds of cellulose, hemicellulose, lignin, and glucose which were independently hydrothermally carbonized and KOH-activated to develop porous adsorbents. The findings of this study highlighted discrete porosity development in the biopolymer-derived activated hydrochar ranging from 591 m2/g for glucose precursor to as high as 2279 m2/g for that cellulose. On the other hand, lignin-based activated hydrochar demonstrated the lowest microporosity (0.084 cm3/g), reflecting its reluctance in transforming the hydrochar carbon matrix into substantially rich micro-cavities, at moderate HTC and CAC conditions. CO2 capture was observed to be the lowest of 1.45 mmol/g for glucose and highest of 2.45 mmol/g for cellulose-derived activated hydrochars, reflecting the direct influence of surface porosity on CO2 adsorbed. Literature data of other lignocellulosic biomass-derived activated hydrochars were combined with results of this study where a statistical analysis revealed the inhibiting role of glucose in pore creation while micropore creation was favored by cellulose and hemicellulose, benefitting CO2 capture. [ABSTRACT FROM AUTHOR] |
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