Synergistic effect of fungal pretreatment and chemical activation on the development of porous carbon from walnut shells for microplastic removal.

Authors

Yajie Diao, Wenjian Liu, Xianwei Cai, Heng Liu, Shu Zhang, Xun Hu

Published in

Bioresource technology. Pages 135733. Aug 30, 2026. Epub Aug 30, 2026.

Abstract

The compact structure of lignocellulosic biomass often limits activator diffusion, restricting pore development in activated carbons. In this study, a synergistic strategy combining Aspergillus niger pretreatment and chemical activation was developed to modify walnut shell structures and enhance pore formation. After pretreatment, walnut shells were activated with ZnCl₂ at 550 °C and K₂C₂O₄ at 800 °C, respectively. Three repeated experiments were performed to ensure data reliability, with errors within 5%. Increasing Aspergillus niger inoculum dosage, the yield of ZnCl₂-activated carbon decreased from 42.6% to 37.7%, and increased the pyrolysis gas yield from 22.8% to 25.7%. For the K₂C₂O₄ activation system, the AC yield decreased from 28.6% to 24.8%, while the gas yield increased from 33.8% to 39.4%. The porous structure formed by fungal pretreatment improved activator penetration and diffusion into the biomass. Furthermore, fungal pretreatment increased the surface area of activated carbons. The surface area of ZnCl₂-activated AC increased from 721.7 to 1555.9 m²/g (116% increase), while that of K₂C₂O₄-activated AC increased from 999.6 to 1220.8 m²/g (22% increase). This strategy optimized pore structures, reduced carbon crystallinity, and enhanced the surface hydrophilicity of AC. The obtained activated carbons exhibited remarkably enhanced adsorption performance toward polystyrene microplastics. This study reveals the synergistic effects of fungal pretreatment and chemical activation in regulating pore structures and adsorption properties of biomass-derived activated carbon. However, the long pretreatment time and reduced solid yield remain challenges for large-scale application. Future studies should optimize microbial systems and process conditions to enhance the economic feasibility of this strategy.

PMID:
42669368
Bibliographic data and abstract were imported from PubMed on 31 Aug 2026.

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