Activation of fungal biomasses with varied activating agents: Evolution of pore structures of activated carbon

Fungi are an important category of biomass resource, which is carbonaceous and could be potential precursors for production of activated carbon (AC). Nonetheless, distinct composition of fungi from woody biomasses might produce AC of different pore characteristics. Herein, two common fungal species, white jade fungus (WJF) and mushrooms, were activated with K₂C₂O₄, ZnCl₂ or H₃PO₄. The resulting ACs were analyzed by using a range of characterization techniques and their performances for adsorption of Cr (VI) were measured. The results indicated that K₂C₂O₄ facilitated cracking of aliphatic structures in WJF, diminishing AC production (25.9%) but enhancing formation of micropores (97.9% and 1108.6 m² g⁻¹). Higher content of unstable organics in mushrooms further lowered AC yield (18.7%) but led to higher specific surface area (1417.2 m² g⁻¹) with K₂C₂O₄ as an activator. ZnCl₂ promoted condensation to generate more AC (44.9%) with abundant mesopores (56.1%) from WJF. Except condensation, Maillard reactions catalyzed by ZnCl₂ retained nitrogen species in AC while cracking with K₂C₂O₄ transferred them into bio-oil. Although H₃PO₄ catalyzed condensation, it could not facilitate pore development. In-situ IR characterization of activation showed that K₂C₂O₄ hindered aromatization while ZnCl₂ facilitated elimination of –OH and CO on nascent AC. This activated outer/inner surface of nascent AC, inducing structural re-construction and forming bulky particles of very densified structures.