Abstract
NH₃ and H₂S are major hazardous odorants emitted from intensive livestock operations, presenting distinct challenges for simultaneous removal. This study evaluates a novel layered filtration system utilizing swine-manure-derived pyrochars produced via a two-stage hydrothermal carbonization (HTC) and pyrolysis process. Chars produced at 350 °C (PMB350) and 550 °C (PMB550) exhibited divergent physicochemical properties. Increasing pyrolysis temperature increased BET surface area (27.94 to 90.00 m2 g− 1) and alkalinity (pH 8.59 to 9.80), while reducing oxygenated surface functionalities. In single-gas fixed-bed tests (100 ppm; 100 mL min− 1), PMB350 exhibited higher NH3 capacity (7.10 mg g− 1) than PMB550 (4.86 mg g− 1), consistent with Brønsted acid–base capture to form surface NH4+. In contrast, PMB550 showed substantially higher H2S capacity (9.70 mg g− 1) than PMB350 (2.54 mg g− 1), reflecting the combined influence of pore development and mineral/alkaline sites. Layered beds (0.25 g + 0.25 g) provided mixed-gas performance (NH3 + H2S, each 100 ppm) with H₂S capacities of 7.15–7.60 mg g− 1 depending on bed order. X-ray photoelectron spectroscopy (XPS) analysis revealed that co-adsorbed NH3 functioned as a surface activator, enhancing the oxidative conversion of H2S to sulfate in the acidic upstream layer (PMB350) and amplifying sulfur mineralization in the alkaline downstream layer (PMB550). The synergy is attributed to an in-situ surface alkalinization mechanism where adsorbed NH3 facilitates H2S dissociation. These findings demonstrate that spatially arranging sorbents with complementary acid-base properties can exploit cooperative chemical interactions, offering a sustainable, high-efficiency strategy for complex odor mitigation.
Data availability
The datasets used or analyzed during the current study are available from the corresponding author upon reasonable request.
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Acknowledgements
This research was supported by the Regional Innovation System & Education (RISE) program (2025-RISE-17-001) through the Jeju RISE center, funded by the Ministry of Education (MOE) and the Jeju Special Self-Governing Province, Republic of Korea and by Basic Science Research Program (RS-2023-00239414) through the National Research Foundation (NRF) funded by the Ministry of Education.
Funding
This research was supported by the Regional Innovation System & Education (RISE) program (2025-RISE-17-001) through the Jeju RISE center, funded by the Ministry of Education (MOE) and the Jeju Special Self-Governing Province, Republic of Korea and by Basic Science Research Program (RS-2023-00239414) through the National Research Foundation (NRF) funded by the Ministry of Education.
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All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Myeongjin Ko and Jae Hac Ko. The first draft of the manuscript was written by Myeongjin Ko and all authors commented on previous versions of the manuscript. All authors read and approved of the final manuscript.
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The datasets used or analyzed during the current study are available from the corresponding author upon reasonable request. The authors have no competing interests to declare that are relevant to the content of this article. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. The authors have no financial or proprietary interest in any material discussed in this article.
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Ko, M., Ko, J.H. Synergistic adsorption of NH3 and H2S over layered hydrochar-derived pyrochars: mechanistic divergence and cooperative acid-base activation. Sci Rep (2026). https://doi.org/10.1038/s41598-026-43340-y
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DOI: https://doi.org/10.1038/s41598-026-43340-y
