DOI number:10.1016/j.watres.2023.120241

Journal:Water Research

Funded by:国家自然科学基金青年项目

Key Words:Black carbon; Hg reduction; In situ electron paramagnetic resonance; Persistent free radicals

Abstract:An accurate depiction of mercury (Hg) reduction is important to predict Hg biogeochemistry in both aquatic and soil systems. Although the photoreduction of Hg is well documented, reduction in the dark is poorly known and is thus the focus of this work. Black carbon (BC), an important constituent of organic matter in environments, can reduce Hg2+ in dark and oxygen-deficient conditions. Fast removal of Hg2+ in BC/Hg2+ solution was observed, with 4.99–86.88 L mg−1h−1 of the reaction rate constant, which could be ascribed to the combined actions of adsorption and reduction. Meanwhile, slow Hg reduction was obtained, compared to Hg removal, with 0.06–2.16 L mg−1h−1 of the reaction rate constant. Thus, in the initial stage, Hg2+ removal was mainly triggered by adsorption, rather than reduction. Afterward, the adsorbed Hg2+ on black carbon was converted into Hg0. Dissolved black carbon and aromatic C[sbnd]H on particulate black carbon were dominant triggers of Hg reduction for black carbon. During Hg reduction, the intastable intermediate, formed in the complex between aromatic C[sbnd]H and Hg2+, behaved as persistent free radicals, which could be detected by in situ electron paramagnetic resonance. Subsequently, the intastable intermediate was mainly converted into C[sbnd]O on black carbon and Hg0. Corresponding results of the present study highlight the important role of black carbon in the Hg biogeochemical cycle.

Indexed by:Journal paper

Document Code:120241

Discipline:Engineering

First-Level Discipline:Environmental Science and Engineering

Document Type:J

Volume:242

ISSN No.:0043-1354

Translation or Not:no

Date of Publication:2023-08-15

Included Journals:SCI

Links to published journals:https://www.sciencedirect.com/science/article/pii/S0043135423006772?pes=vor

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