Novel freestanding carbons for micropollutants removal through sustainable processes

  • Neuartige freistehende Kohlenstoffe für die Entfernung von Mikroverunreinigungen in nachhaltigen Prozessen

Mohseni, Mojtaba; Wessling, Matthias (Thesis advisor); van Hullebusch, Eric D. (Thesis advisor)

Aachen : RWTH Aachen University (2022)
Book, Dissertation / PhD Thesis

In: Aachener Verfahrenstechnik Series AVT.CVT - Chemical Process Engineering 27 (2022)
Page(s)/Article-Nr.: 1 Online-Ressource : Illustrationen

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2022

Abstract

Nowadays, the occurrence of organic micropollutants (OMPs), especially pharmaceuticals, in water bodies has caused widespread concerns due to their negative impacts, e.g., bioaccumulating in living organisms and developing antibiotic-resistant bacteria and genes. On the other hand, conventional wastewater treatment plants, including a main biological step, fail to efficiently remove highly mobile and recalcitrant pharmaceuticals, posing new challenges for the clean water supply. This thesis introduces novel freestanding carbons that can serve as an adsorbent, an electrode, or both to remove OMPs via adsorption, (electro-)Fenton-based oxidation, or a combination of them in a so-called cyclic process, respectively. Such self-standing carbon materials can facilely incorporate different catalysts nanoparticles inside their structure. Two self-standing carbon microtubes were synthesized using carbon nanotubes (CNT) as the main constituent, mixed with powdered activated carbons (PAC) and Fe3O4 nanoparticles to serve as a micro-and mesoporous adsorbent (PAC/CNT microtube) and a Fe-incorporated carbon electrode (Fe3O4 /CNT microtube), respectively. The addition of PAC to the CNT matrix increased the specific surface area by introducing micropores as high energy centers for OMPs removal, especially at low equilibrium concentrations. A temperature-assisted Fenton oxidation was proposed to regenerate the SMX-saturated PAC/CNT microtube and reuse it for 12 consecutive cycles. Compared to the room temperature oxidation, the temperature-assisted Fenton showed an enhanced regenerated capacity in each cycle and extended durability of the adsorbent by mitigating the adsorption of undesired compounds during the Fenton process. Fe3O4 /CNT microtubes proved to degrade CBZ as an efficient cathode for heterogeneous electro-Fenton (HEF) with good reusability and minimal catalysts leaching in acidic environments. Moreover, as a green alternative to CNT-based carbons, a novel synthesis method to fabricate monolithic carbons was introduced using chitosan and sucrose as bio-based precursors. Final monolithic carbons possess high specific surface areas (up to 703 m2/g), a hierarchical porosity, and nitrogen and oxygen as heteroatoms. Monolithic carbons served as an adsorbent with adequate separation properties to adsorb SMX, being comparable to commercial granular carbons despite having 50 % less specific surface area. Furthermore, cylindrical and tubular carbons were deployed directly as electrodes and gas diffusion electrodes (GDE), respectively. Next, successful incorporation of Fe3O4 into bio-based carbons was carried out, and final Fe-containing carbons were used as electrodes and GDEs and proved to remove both SMX and CBZ and a mixture of them effectively at pH 3 and 7.This thesis emphasizes the advantages of self-standing carbons, with scaling-up perspectives, to develop efficient, more sustainable, and cost-effective processes for clean water supply and pave the way for implementing tangible (micro) tubular reactors.

Institutions

  • Chair of Chemical Process Engineering and Institute of Process Engineering [416110]

Identifier

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