New methods for assessing electron storage capacity and redox reversibility of biochar

Copyright © 2018 Elsevier Ltd. All rights reserved..

Black carbon such as biochar has been shown to support microbial redox transformation by accepting and/or donating electrons. Electron storage capacity (ESC) is an important property that determines the capacity of a biochar to mediate redox processes in natural and engineered systems. However, it remained unclear whether a biochar's ESC is constant and reversible and if so to what extent, over what redox potential range ESC is distributed, and what fraction of the ESC is microbially accessible. In this study, we developed chemical methods that employed combinations of reductants and oxidants of different potentials - Ti(III) citrate, ferricyanide, dithionite, and dissolved O2 - to measure the ESC of Soil Reef biochar, a wood-derived biochar that can serve as an electron donor or acceptor for Geobacter metallireducens. For a given oxidant-reductant pair, the ESC obtained over multiple redox cycles was constant and fully reversible, though lower than that of the virgin biochar. Pore diffusion within biochar particles was rate-limiting and controlled the timescale for redox equilibrium. Results suggest that redox-facile functional groups in biochar were distributed over a broad range of potentials. The ESC measured using dithionite indicates approximately 22% of the biochar's reversible ESC was accessible to G. metallireducens. We propose that reversible ESC may be regarded as a constant and quantifiable property of black carbon.

Medienart:

E-Artikel

Erscheinungsjahr:

2019

Erschienen:

2019

Enthalten in:

Zur Gesamtaufnahme - volume:215

Enthalten in:

Chemosphere - 215(2019) vom: 01. Jan., Seite 827-834

Sprache:

Englisch

Beteiligte Personen:

Xin, Danhui [VerfasserIn]
Xian, Minghan [VerfasserIn]
Chiu, Pei C [VerfasserIn]

Links:

Volltext

Themen:

16291-96-6
Biochar
Charcoal
Chemical oxidation/reduction
Electron storage capacity
Journal Article
Pore diffusion
Rate-limiting step
Redox reversibility
Soil

Anmerkungen:

Date Completed 20.12.2018

Date Revised 20.12.2018

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.chemosphere.2018.10.080

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM289940915