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

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; Davidsson, Åsa; Cimbritz, Michael; Gamoń, Filip; Pierpaoli, Mattia

DOI:

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 g14), indicating limited site accessibility. In contrast, SSA-based electrodes offered both higher BET and EASA values (up to 328.6 cm2 g14), improving adsorption and oxidation performance. Electrochemical oxidation of 14C-labelled micropollutants (BPA, diclofenac, , 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.

Keywords

Persistent organic pollutants ; Electrochemical oxidation ; Wastewater treatment ; Upcycling ; Carbon-based electrodes ; DFT simulations

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Polyacrylonitrile

A97130525014-41-9homopolymer，average Mw 150,000

Polyacrylonitrile

65.0/500g

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