Unveiling the hidden intrinsic porosity of marine biomass-derived carbon: Eliminating pore-blocking minerals

Abstract

In the pursuit of carbon neutrality, marine biomass (MB) has emerged as a promising alternative to traditional carbon sources. This study endeavors to establish an economically viable pathway to derive porous carbon materials from MB. Simple pyrolysis of MB resulted in a MB-based carbon (MBC) characterized by a negligible open-pore structure. However, subsequent water washing transformed it into a porous material. N₂ adsorption tests revealed that the pyrolysis temperature and washing method substantially influenced the specific surface area (SSA) and pore volume of the MBC. While the catalytic activation function of elements inherent in MB, such as Na, Mg, K, Ca, and Cl, rendered MBC inherently porous, these elements also induced an initial pore-blocking effect that concealed the pores. Subsequent washing with water nearly eradicated Na, K, and Cl from MBC, making a number of the concealed pores accessible. Furthermore, a CO₂ aeration washing method effectively eliminated Mg and Ca elements from MBC, resulting in a substantial increase in SSA (>1000 m²/g) without the need for additional activation processes. Based on an understanding of the dual role of the elements naturally present in MB, this study demonstrates a potential strategy for environmentally friendly and cost-effective porous carbon production.