H. Attigah, L. Zimmerman, A. Mali, T. Uwaike, S. Mantripragada, L. Zhang
Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University,,
United States
Keywords: CO2 capture, hydrothermal liquefaction, algae derived carbon, polyethyleneimine modification
Summary:
Given the urgent need to mitigate rising atmospheric CO₂ levels and meet global climate targets, developing low-cost, scalable, and sustainable carbon capture technologies is more critical than ever. Hydrothermal liquefaction (HTL) offers a sustainable pathway for converting wet biomass into bio-oil and carbon-rich byproduct, yet the CO₂ capture potential of the by-product remains underexplored. This study investigates the adsorption performance of algae-derived carbon (ADC), a by-product of HTL processing of microalgae, for CO₂ capture at ambient conditions. ADC synthesized at 300 °C was chemically activated with KOH at 800 °C (1:1 mass ratio), yielding a microporous structure with significantly enhanced surface area and pore volume, as confirmed by BET analysis. Further surface functionalization with polyethyleneimine (PEI) introduced amine groups, improving CO₂ affinity and selectivity. Comprehensive material characterizations using SEM, XPS, FTIR, and BET revealed that PEI-modified ADC exhibited superior CO₂ uptake at 1 bar and 25 °C, along with excellent CO₂/N₂ selectivity. These findings demonstrate the viability of ADC materials as efficient, low-cost, and sustainable adsorbents for ambient CO₂ capture, contributing to carbon neutrality and climate change mitigation goals.