Mechanisms of mercury (Hg) and methylmercury (CH3Hg+) removal by pristine and thiol-modified açaí waste nanobiochar

Soares, M. B., Hurtarte, L. C. C., Sizmur, T. ORCID: https://orcid.org/0000-0001-9835-7195, Nehzati, S. and Alleoni, L. R.F. (2026) Mechanisms of mercury (Hg) and methylmercury (CH3Hg+) removal by pristine and thiol-modified açaí waste nanobiochar. Environmental Science and Pollution Research. ISSN 1614-7499 (In Press)

Abstract/Summary

Mercury (Hg) contamination remains a global environmental challenge, driven by sources such as artisanal gold mining, industrial emissions, and coal combustion. Developing efficient and sustainable remediation strategies is therefore critical. Here, we evaluate for the first time the mechanisms controlling Hg and methylmercury (CH3Hg+) removal using nanobiochar derived from açaí (Euterpe oleracea Mart) seed residues and its thiol-functionalized counterpart. Nanobiochar (<50 nm) was produced via pyrolysis at 600°C and chemically modified to enhance sorption performance. Thiol functionalization increased maximum sorption capacities by 29% for Hg2+ (from 299 to 385 mg g-1) and 61% for CH₃Hg⁺ (from 102 to 164 ng g-1), while also reducing desorption. Spectroscopic analyses (XPS and EXAFS) revealed that Hg immobilization is primarily driven by the formation of stable Hg–S species, including metacinnabar (β-HgS), highlighting a shift from weaker ionic interactions to covalent bonding. This mechanistic evidence demonstrates that surface functionalization not only enhances sorption capacity but also promotes long-term stability of retained Hg species. By coupling waste valorization with advanced spectroscopic insights, this study provides a novel framework for designing high-performance materials for Hg remediation in contaminated environments.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/130839
Refereed	Yes
Divisions	Science > School of Archaeology, Geography and Environmental Science > Department of Geography and Environmental Science Interdisciplinary centres and themes > Soil Research Centre
Publisher	Springer
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