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Author Spotlight: On-Site Biochar Production for Woody Debris Incineration in Forestry
Published on: January 5, 2024
Optimized one-step pyrolysis synthesis of zinc-modified sludge biochar for enhanced perfluorooctane sulfonate removal
Muzi Li1, Ranbin Liu1, Xiaodi Hao1
1Key Laboratory of Urban Stormwater System and Water Environment, Ministry of Education/Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies, Beijing University of Civil Engineering & Architecture, Beijing, 100044, China.
Abstract:
Perfluoroocatane sulfonate (PFOS) has drawn increasing global attention due to its environmental omnipresence and adverse health effects. This study presents a synergistic strategy to address the dual challenge of legacy PFOS contamination and sustainable sewage sludge disposal by developing a novel, zinc-modified sludge-based biochar (Zn/SBC) for highly efficient PFOS removal. The innovation lies in the one-step pyrolysis using ZnCl2 as an activator, which dramatically enhanced the specific surface area by 50-fold (to 261.33 m2/g) by creating a well-developed micro- and mesoporous structure. Under optimized conditions, 26%Zn/SBC exhibited a superior PFOS adsorption capacity of 60.14 mg/g, 5.83 times than that of pristine biochar, and achieved >99% removal across a wide pH range (3-11). The material exhibited remarkably stable performance, sustaining a removal efficiency over 93.6% in the presence of high concentration of competing ions and humic acid. After 5 cycles of repeated uses, 26%Zn/SBC remained highly reactive in adsorption for PFOS. In addition, the superior adsorption of PFOS by optimized 26%Zn/SBC is attributed to a unique concurrent mechanism, including electrostatic attraction facilitated by the elevated point of zero charge (pHPZC = 8.1), surface complexation with Zn/ZnO sites, π-anion interaction, and hydrophobic effects. This study not only presents a high-performance and low-cost adsorbent for PFOS remediation, which holds the potential for more cost-effective PFAS removal, but also establishes a sustainable "waste-to-wealth" strategy, paving the way for practical solutions to concentration persistent organic pollutants in aquatic environments.
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