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Closed-loop upcycling of sewage sludge products into sp2-C-rich electrodes for pollutant oxidation : tracking mineralization by 14C-labeling

Łepek, Angelika ; Szopińska, Małgorzata ; Kaczmarzyk, Iwona ; Olejnik, Adrian ; Falås, Per LU ; Davidsson, Åsa LU orcid ; Cimbritz, Michael LU ; Gamoń, Filip and Pierpaoli, Mattia LU (2025) In Chemical Engineering Journal 520.
Abstract

To address the need for sustainable wastewater treatment, we developed sp2‑carbon-rich, hierarchically porous electrodes by upcycling sewage sludge ash (SSA) and biochar (CB) using a hybrid 3D printing and microwave plasma-enhanced chemical vapor deposition (MPECVD) approach. The CB-containing electrode exhibited a 260-fold increase in BET surface area (0.15 to 40.6 m2 g−1), but the lowest electrochemically active surface area (EASA = 18.3 cm2 g−1), indicating limited site accessibility. In contrast, SSA-based electrodes offered both higher BET and EASA values (up to 328.6 cm2 g−1), improving adsorption and oxidation performance. Electrochemical oxidation of... (More)

To address the need for sustainable wastewater treatment, we developed sp2‑carbon-rich, hierarchically porous electrodes by upcycling sewage sludge ash (SSA) and biochar (CB) using a hybrid 3D printing and microwave plasma-enhanced chemical vapor deposition (MPECVD) approach. The CB-containing electrode exhibited a 260-fold increase in BET surface area (0.15 to 40.6 m2 g−1), but the lowest electrochemically active surface area (EASA = 18.3 cm2 g−1), indicating limited site accessibility. In contrast, SSA-based electrodes offered both higher BET and EASA values (up to 328.6 cm2 g−1), improving adsorption and oxidation performance. Electrochemical oxidation of 14C-labelled micropollutants (BPA, diclofenac, carbamazepine, and PFOA) exhibited pollutant-specific removal pathways. SSA electrodes enhanced BPA adsorption and mineralization, achieving a 1.6-fold faster 14CO₂ production rate. While CBZ and DIC were partially mineralised, no measurable 14CO₂ formation was observed for PFOA, suggesting a different removal mechanism. An inverse correlation was observed between mineralization rates and DFT-calculated bond cleavage energies. These findings highlight the practical potential of upcycled electrodes to achieve efficient mineralization of persistent organic pollutants. This closed-loop strategy offers an environmentally viable approach to turning waste into functional materials for advanced wastewater treatment processes.

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Carbon-based electrodes, DFT simulations, Electrochemical oxidation, Persistent organic pollutants, Upcycling, Wastewater treatment
in
Chemical Engineering Journal
volume
520
article number
166284
pages
10 pages
publisher
Elsevier
external identifiers
  • scopus:105011478804
ISSN
1385-8947
DOI
10.1016/j.cej.2025.166284
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Author(s)
id
1c5c89a4-38c2-433e-9360-f5f833fc8214
date added to LUP
2025-08-25 11:07:45
date last changed
2025-08-25 13:53:35
@article{1c5c89a4-38c2-433e-9360-f5f833fc8214,
  abstract     = {{<p>To address the need for sustainable wastewater treatment, we developed sp<sup>2</sup>‑carbon-rich, hierarchically porous electrodes by upcycling sewage sludge ash (SSA) and biochar (CB) using a hybrid 3D printing and microwave plasma-enhanced chemical vapor deposition (MPECVD) approach. The CB-containing electrode exhibited a 260-fold increase in BET surface area (0.15 to 40.6 m<sup>2</sup> g<sup>−1</sup>), but the lowest electrochemically active surface area (EASA = 18.3 cm<sup>2</sup> g<sup>−1</sup>), indicating limited site accessibility. In contrast, SSA-based electrodes offered both higher BET and EASA values (up to 328.6 cm<sup>2</sup> g<sup>−1</sup>), improving adsorption and oxidation performance. Electrochemical oxidation of <sup>14</sup>C-labelled micropollutants (BPA, diclofenac, carbamazepine, and PFOA) exhibited pollutant-specific removal pathways. SSA electrodes enhanced BPA adsorption and mineralization, achieving a 1.6-fold faster <sup>14</sup>CO₂ production rate. While CBZ and DIC were partially mineralised, no measurable <sup>14</sup>CO₂ formation was observed for PFOA, suggesting a different removal mechanism. An inverse correlation was observed between mineralization rates and DFT-calculated bond cleavage energies. These findings highlight the practical potential of upcycled electrodes to achieve efficient mineralization of persistent organic pollutants. This closed-loop strategy offers an environmentally viable approach to turning waste into functional materials for advanced wastewater treatment processes.</p>}},
  author       = {{Łepek, Angelika and Szopińska, Małgorzata and Kaczmarzyk, Iwona and Olejnik, Adrian and Falås, Per and Davidsson, Åsa and Cimbritz, Michael and Gamoń, Filip and Pierpaoli, Mattia}},
  issn         = {{1385-8947}},
  keywords     = {{Carbon-based electrodes; DFT simulations; Electrochemical oxidation; Persistent organic pollutants; Upcycling; Wastewater treatment}},
  language     = {{eng}},
  month        = {{09}},
  publisher    = {{Elsevier}},
  series       = {{Chemical Engineering Journal}},
  title        = {{Closed-loop upcycling of sewage sludge products into sp<sup>2</sup>-C-rich electrodes for pollutant oxidation : tracking mineralization by <sup>14</sup>C-labeling}},
  url          = {{http://dx.doi.org/10.1016/j.cej.2025.166284}},
  doi          = {{10.1016/j.cej.2025.166284}},
  volume       = {{520}},
  year         = {{2025}},
}