TDB
Activité scientifique
Profil chercheur
Enseignant-chercheur à l’Université de Yaoundé I.
Publications scientifiques
Cyrille Djoko Mbiagaing, Gaëlle Ngnie, Gustave Kenne Dedzo, Emmanuel Ngameni
Applied Catalysis A General
Ruth Valerie Ngnokam Nkouonga, Gaëlle Ngnie, Hervé L. Tcheumi, Jordan Jeazet Fouelefack, Cyrille Djoko Mbiagaing, Gustave Kenne Dedzo et 1 autre(s)
New Journal of Chemistry
The recycling of bio-sourced materials derived from forest exploitation and agriculture, in several applications including bioenergy production with less environmental footprint is an actual concern. In the present work, a...
Cedric M. Dieuhou, Gaëlle Ngnie, Jean Jacques Kouadjo Tchekwagep, Barbara Rodrigue Eloundou Mbole, Hervé Kouamo Tchakouté, Zihao Li et 3 autre(s)
Archives of Civil and Mechanical Engineering
Ruth Valerie Ngnokam Nkouonga, Gaëlle Ngnie, Hervé L. Tcheumi, Emmanuel Ngameni
International Journal of Environmental & Analytical Chemistry
The development of analytical tools for pesticide pollution control is an important challenge to monitor pollution associated to these widely used compounds. In the present work, sawdust, a waste biomass, was modified using concentrated phosphoric acid. The resulting material was used to modify a glassy carbon electrode, and applied for the electrochemical detection of paraquat, a non-selective herbicide, known for its extremely harmful effects on living organisms. Characterisation of the phosphoric acid modified sawdust by XRD, FTIR spectroscopy, XPS and SEM/EDX reveals a structure close to that of hydrochars obtained by hydrothermal treatment of biomass. Electrochemical characterisations (cyclic voltammetry and electrochemical impedance spectroscopy) showed that this material also contains anionic groups (mainly phosphonate and carboxylate) which facilitated the selective accumulation of cationic species such as paraquat. Adsorption studies demonstrated the material’s high affinity for paraquat, with an adsorption capacity of 0.45 mmol g−1, at least 12-folds higher than that recorded on the untreated sawdust. Used as an electrode modifier, the sensor obtained showed a detection limit of 0.24 nM in the investigated concentration range (5 nM to 60 nM). This sensor was effective for the detection of this pesticide in real samples (river and tap water) and in commercial formulation with excellent precision and recovery capacity. These results highlight the dual potential of the synthesised material as both an efficient adsorbent for the removal of paraquat as well as an electrode modifier for trace-level sensing of paraquat in aqueous environments.
Gaëlle Ngnie, Rock Ambela Atangana, Grace Ingrid Tomou-Mbahim, Lionel Magellan Sambang, Gustave Kenne Dedzo, Hervé Kouamo Tchakouté et 2 autre(s)
RSC Applied Interfaces
Favorable interactions between alkaline treated sawdust and metakaolin/sodium waterglass geopolymer matrix, with substantial improvement of compressive strength and cations adsorption.
Cyrille Djoko Mbiagaing, Anselme Junior Tagne, Gaëlle Ngnie, Gustave Kenne Dedzo, Emmanuel Ngameni
New Journal of Chemistry
Successful chemical and electrochemical catalytic reduction of 4-chloro-2-nitroaniline onto palladium nanoparticle supported organo-kaolinite.
Gaëlle Ngnie, Daniela Baitan, Gustave Kenne Dedzo, Christian Detellier
Fuel
Gustave Kenne Dedzo, Emmanuel Pameté, Melissa Ramel Topet Saheu, Gaëlle Ngnie, Charles Péguy Nanseu‐Njiki, Christian Detellier et 1 autre(s)
Journal of Electroanalytical Chemistry
Gustave Kenne Dedzo, Gaëlle Ngnie, Christian Detellier
ACS Applied Materials & Interfaces
The synthesis of selectively deposited palladium nanoparticles (PdNPs) inside tubular halloysite lumens is reported. This specific localization was directed by the selective modification of the aluminol surfaces of the clay mineral through stable Al-O-C bonds. An ionic liquid (1-(2-hydroxyethyl)-3-methylimidazolium) was grafted onto halloysite following the guest displacement method (generally used for kaolinite) using halloysite-DMSO preintercalate. The characterization of this clay nanohybrid material (XRD, NMR, TGA) showed characteristics reminiscent of similar materials synthesized from kaolinite. The grafting on halloysite lumens was also effective without using the DMSO preintercalate. The presence of these new functionalities in halloysite directs the synthesis of uniform PdNPs with size ranging between 3 and 6 nm located exclusively in the lumens. This results from the selective adsorption of PdNPs precursors in functionalized lumens through an anion exchange mechanism followed by in situ reduction. In contrast, the unmodified clay mineral displayed nanoparticles both inside and outside the tubes. These catalysts showed significant catalytic activity for the reduction of 4-nitrophenol (4-NP). The most efficient catalysts were recycled up to three times without reducing significantly the catalytic activities.
Gaëlle Ngnie, Gustave Kenne Dedzo, Christian Detellier
Dalton Transactions
Palladium nanoparticles (PdNPs) were deposited on the surface of the modified clay mineral, kaolinite. To improve compatibility, abundance and control of the size of the nanoparticles, kaolinite was modified by the grafting of an amino alcohol (triethanolamine (TEA)) and an ionic liquid (1-(2-hydroxyethyl)-3-methylimidazolium (ImIL)). Characterization techniques (XRD, TGA, solid state (13)C NMR and FTIR spectroscopy) confirmed the effective grafting of these compounds on the internal surface of kaolinite. After the synthesis of PdNPs onto clay particles, TEM allowed the visualization of abundant PdNPs with sizes ranging from 4 to 6 nm, uniformly distributed onto the platelets of modified kaolinite. Unmodified clay showed low abundance and random distribution of the nanoparticles. The catalysts obtained were effective for the catalytic reduction of 4-nitrophenol (4-NP), the material with TEA being the most effective. These materials have exhibited excellent performance during the Heck and particularly the Suzuki-Miyaura coupling reactions, with reaction yields up to 100%. These catalysts showed a very slight loss in activity for three consecutive catalytic cycles (less than 10% decrease of the activity compared to the first cycle). This was an evidence that the prior grafting modification of kaolinite helps in significantly improving the quality of the synthesized NPs and also promotes their strong attachment onto the clay mineral surface.
Profil chercheur
Publications scientifiques
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2 publications
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