Site institutionnel du Laboratoire Ampère - CNRS UMR5005

Abdelghani GHANAM defends his PhD on Nov. 25, 2022.
Place : University Hassan II, Casablanca, Faculty of Sciences et Technics, Mohammedia, Maroc

Jury :
Rapporteurs : GORGY, Karine (Univ. Grenoble Alpes); BRETT, M.A. Christophe (Univ. de Coimbra)
Examinateurs : IDRISSI, Laila (Univ. Hassan II. Casablanca); JAMA, Charafeddine (Univ. Centrale de Lille); LAURENCEAU,Emmanuelle (Ecole Centrale de Lyon)
Invité: HADDOUR, Naoufel (Ecole Centrale de Lyon)
Encadrement Ampère : AMINE, Aziz (Univ. Hassan II. Casablanca); BURET, François (Ecole Centrale de Lyon)

Abstract :
Rapid industrialization and population growth are now the main causes of energy and environmental problems in sanitation. Conventional wastewater treatment technologies (treatment plants, WWTPs) are energy- and cost-intensive. Furthermore, WWTPs are not qualified to treat non-biodegradable contaminants (antibiotics, heavy metals, etc.). A highly toxic discharge can disrupt traditional biological processes in WWTPs. On-line monitoring of wastewater quality is therefore crucial for the safe operation of WWTPs. In this context, this thesis aimed at the development of new self-powered (bio)sensors based on organic fuel cell (FC) technology. (Bio)sensors that can offer the advantage of being simultaneously tools to treat water, produce energy, and monitor in real-time the (bio)toxicity in wastewater. First, palladium- and gold-based abiotic catalysts were synthesized and tested for glucose electrooxidation reaction (GOR) in a neutral medium (pH 7.4). A simple and cost-effective electrochemical method was used to deposit the catalysts on the surface of screen-printed electrodes (SPCE) modified with carbon nanotubes (CNT). The results obtained showed that shape and size of metal catalysts have a significant effect on the electrocatalytic activity towards GOR. And thanks to the intrinsic properties of each individual metal catalyst, both catalysts showed a synergistic effect. The anode with the highest sensitivity to glucose was chosen as anode in a novel membrane-less non-enzymatic glucose fuel cell (n-EFC) configuration. The anode was then connected to an air cathode composed of Pt-coated carbon cloth catalyst for oxygen electroreduction. This abiotic cell showed that a maximum power density of 129 ± 11 µW.cm-2 at 20 mM glucose was achieved. Hence, the glucose-O2 n-EFC could be an alternative to expensive natural enzymes in direct glucose fuel cell applications. Second, optimization of particular operating parameters in microbial fuel cells (MFCs) is essential to achieve better performance. Indeed, the 3D pristine carbon felt (CF) anode was subjected to different treatment modes, including acid-heat treatment as well as coating with highly conductive carbon nanofibers (CNFs). As a result, the pristine CF anode provided higher power, offering great prospects for improving PACM performance with reduced material cost. These anodes were then used in an innovative MFC architecture, fabricated at Ampère laboratory, to study the cathode material. Moreover, a new strategy for air cathode fabrication has been proposed, using PTFE spray to develop carbon-free air diffusion layers. Using this MFC architecture, we can with only one MFC and biofilm: (1) characterize different cathode materials without damaging or disturbing the developed anodic biofilm; (2) optimize different parameters (inter-electrodes distance, number of anodes and cathodes, etc). Finally, self-powered biosensors based on PACMs have been proposed for real-time detection of biotoxicity in wastewater. Selectivity and sensitivity of the biosensors have been enhanced by adapting anodic biofilms to the targeted pollutant. Neomycin sulfate (NS) and Pb2+ ions were used as toxicity models. Using pollutant-adapted biofilms could be a new approach to improve the specificity of MFC-based biosensors.

Keywords :
Microbial fue,l cell Bacteria, Air cathode, Carbon felt, Biofilm, Anode modification, Adapted biofilm, Toxicity biosensor, Glucose, Non-enzymatic catalyst, Electrodeposition, Carbon nanotube, Non-enzymatic fuel cell, Membraneless