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Dive into the research topics where Didier Floner is active.

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Featured researches published by Didier Floner.


Electrochimica Acta | 2001

Biomass conversion II: simultaneous electrosyntheses of furoic acid and furfuryl alcohol on modified graphite felt electrodes☆

G. Chamoulaud; Didier Floner; Claude Moinet; C. Lamy; E.M. Belgsir

Simultaneous electrocatalytic production of furoic acid and furfuryl alcohol from furfural is performed on modified graphite felt electrodes in aqueous electrolyte using a separated flow cell.


Journal of Hazardous Materials | 2014

Indirect electroreduction as pretreatment to enhance biodegradability of metronidazole.

I. Saidi; Isabelle Soutrel; Didier Floner; Florence Fourcade; Nizar Bellakhal; Abdeltif Amrane; Florence Geneste

The removal of metronidazole, a biorecalcitrant antibiotic, by coupling an electrochemical reduction with a biological treatment was examined. Electroreduction was performed in a home-made flow cell at -1.2V/SCE on graphite felt. After only one pass through the cell, analysis of the electrolyzed solution showed a total degradation of metronidazole. The biodegradability estimated from the BOD5/COD ratio increased from 0.07 to 0.2, namely below the value usually considered as the limit of biodegradability (0.4). In order to improve these results, indirect electrolysis of metronidazole was performed with a titanium complex known to reduce selectively nitro compounds into amine. The catalytic activity of the titanium complex towards electroreduction of metronidazole was shown by cyclic voltammetry analyses. Indirect electrolysis led to an improvement of the biodegradability from 0.07 to 0.42. To confirm the interest of indirect electroreduction to improve the electrochemical pretreatment, biological treatment was then carried out on activated sludge after direct and indirect electrolyses; different parameters were followed during the culture such as pH, TOC and metronidazole concentration. Both electrochemical processes led to a more efficient biodegradation of metronidazole compared with the single biological treatment, leading to an overall mineralization yield for the coupling process of 85%.


Talanta | 2012

Flow electrochemical analyses of zinc by stripping voltammetry on graphite felt electrode

Bogdan Feier; Didier Floner; Cecilia Cristea; Ede Bodoki; Robert Sandulescu; Florence Geneste

A flow sensor for trace analysis of zinc, using graphite felt as working electrode is reported here. A flow cell, well-adapted to 3-D porous electrodes and capable to do both the preconcentration step at a cathodic potential and the stripping of the zinc was successfully developed. It was demonstrated that this cell allows to obtain better electrochemical signals for Zn(2+) compared to a standard three-electrodes cell and that the percolation during accumulation increases the kinetics of electrodeposition. The influence on Zn(2+) signal of the deposition potential, the time of deposition and the flow rate was studied. The resulting sensor shows a linear response towards Zn(2+) with a linear range of 10(-6)-10(-4)M and a limit of detection of 5×10(-7) M for an analysis time of 5 min. The interferences study showed that the Cr(3+), Pb(2+), Cd(2+) ions have a small effect on the Zn electrochemical signal, whereas Fe(3+), Cu(2+), Co(2+) and Ni(2+) ions strongly influence it. The electrode was tested on real samples (tap water spiked with Zn(2+), food supplement) with a good recovery by applying the standard addition method.


Electrochimica Acta | 1997

Indirect electrolysis involving an ex-cell two-phase process. Reduction of nitrobenzenes with a titanium complex as mediator

Didier Floner; Laurence Laglaine; Claude Moinet

Indirect electrolysis of nitrobenzenes, in organic solvent (dichloromethane, toluene), with a titanium complex (C5H5)2Ti+ used as mediator in aqueous acidic medium, is performed by phase transfer reaction in a reactor located out of the electrolytic cell. Nitrocompounds are selectively reduced to aminoderivatives and the resulting oxidized form of complex (C5H5)2TiOH+ is reduced at a graphite felt cathode by continuous recycling of the aqueous solution until the complete reduction of nitrocompounds. Dinitrocompounds are directly reduced to diamino derivatives. Advantages and limitations of the procedure are shown. Formation of an intermediate between the nitrocompound and the reduced form of the mediator is postulated to explain the selectivity of the reduction.


New Journal of Chemistry | 2012

Rate enhancement of the catechol oxidase activity of a series of biomimetic monocopper(II) complexes by introduction of non-coordinating groups in N-tripodal ligands

Ronan Marion; Nidal Saleh; Nicolas Le Poul; Didier Floner; Olivier Lavastre; Florence Geneste

Asymmetrical N-tripodal ligands have been synthesized in three steps. Diversity has been introduced at the first step of the synthesis by adding pyrazine, pyridine, benzyl and thiophene rings. The corresponding CuII complexes have been prepared by reaction with CuCl2 and characterized by Electron Paramagnetic Resonance (EPR), UV-Vis spectroscopies and cyclic voltammetry. The data show that the ligand coordinates to CuII in a mononuclear fashion in solution and that the complexes display a square pyramidal geometry. All complexes are characterized by a quasi-reversible one-electron redox behavior in acetonitrile. The ability of the complexes to oxidize 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone has been studied and the results show that the rate of the reaction depends on the basicity and the steric hindrance of the heterocyclic donor. Best results have been obtained with CuII complexes coordinated to bidentate ligands, since they facilitate the approach and the coordination of catechol to the metal. Particularly, the introduction of a thiophenyl group to mimic the sulfur atom at proximity to the catalytic center in the catechol oxidase protein structure improves the catalytic activity of the complex.


Journal of Inorganic Biochemistry | 2011

Characterization and catechole oxidase activity of a family of copper complexes coordinated by tripodal pyrazole-based ligands.

Ronan Marion; M. Zaarour; N. A. Qachachi; Nidal Saleh; Frédéric Justaud; Didier Floner; Olivier Lavastre; Florence Geneste

A family of tripodal pyrazole-based ligands has been synthesized by a condensation reaction between 1-hydroxypyrazoles and aminoalcohols. The diversity was introduced both on the substituents of the pyrazole ring and on the side chain. The corresponding copper(II) complexes have been prepared by reaction with CuCl(2) in tetrahydrofuran. They have been characterized by EPR, UV spectroscopy and cyclic voltammetry. The absence of the half-field splitting signals in EPR suggests that the complex exists in solution as mononuclear species. The influence of substituents and side chain of the tripodal ligand on the catecholase activity of the complexes was studied. The reaction rate depends on two factors. First, the presence of an oxygen atom in the third position of the side chain should be avoided to keep the effectiveness of the reaction. Second, the electronic and steric effects of substituents on the pyrazole ring strongly affect the catalytic activity of the complex. Thus, best results were obtained with complexes containing unsubstituted pyrazole based-ligands. Kinetic investigations with the best catalyst based on the Michaelis-Menten model show that the catalytic activity of the mononuclear complex is close to that of some dicopper complexes described in literature.


Electrochimica Acta | 1997

Indirect electroreduction of nitrobenzenes ortho-substituted by ester, carbonate, amide or carbamate group

Thierry Jan; Didier Floner; Claude Moinet

Abstract Indirect electrolysis of various nitrobenzenes ortho -substituted by ester (OCOR), carbonate (OCO 2 R), amide (NHCOR) or carbamate (NHCO 2 R) group in dichloromethane is performed with a titanium complex (C 5 H 5 ) 2 Ti + in 1 N aqueous sulphuric acid. Nitro compounds are selectively reduced to amino derivatives. Rearrangement of anilines ortho -substituted by ester or carbonate group into N -acylated o -aminophenol takes place in situ . 2-Substituted benzimidazoles are prepared from N -acylated o -phenylenediamines by heating in boiling acetic acid.


Journal of Hazardous Materials | 2017

Direct and indirect electrochemical reduction prior to a biological treatment for dimetridazole removal

Melika Zaghdoudi; Florence Fourcade; Isabelle Soutrel; Didier Floner; Abdeltif Amrane; Hager Maghraoui-Meherzi; Florence Geneste

Two different electrochemical reduction processes for the removal of dimetridazole, a nitroimidazole-based antibiotic, were examined in this work. A direct electrochemical reduction was first carried out in a home-made flow cell in acidic medium at potentials chosen to minimize the formation of amino derivatives and then the formation of azo dimer. Analysis of the electrolyzed solution showed a total degradation of dimetridazole and the BOD5/COD ratio increased from 0.13 to 0.24. An indirect electrochemical reduction in the presence of titanocene dichloride ((C5H5)2TiCl2), which is used to reduce selectively nitro compounds, was then investigated to favour the formation of amino compounds over hydroxylamines and then to prevent the formation of azo and azoxy dimers. UPLC-MS/MS analyses showed a higher selectivity towards the formation of the amino compound for indirect electrolyses performed at pH 2. To confirm the effectiveness of the electrochemical reduction, a biological treatment involving activated sludge was then carried out after direct and indirect electrolyses at different pH. The enhancement of the biodegradability was clearly shown since mineralization yields of all electrolyzed solutions increased significantly.


Environmental Technology | 2017

Sulfamethazine removal by means of a combined process coupling an oxidation pretreatment and activated sludge culture – Preliminary results

Imen Saidi; Florence Fourcade; Didier Floner; Isabelle Soutrel; Nizar Bellakhal; Abdeltif Amrane; Florence Geneste

ABSTRACT A coupled electrochemical process and biological treatment was used to remove a biorecalcitrant antibiotic: sulfamethazine (SMT). The pretreatment was performed in a home-made flow cell involving graphite felt as a working electrode at potentials of 1 and 1.6 V/saturated calomel electrode (SCE); it was followed by a biological process involving activated sludge purchased from a local wastewater treatment plant. Activated sludge cultures of pretreated and non-pretreated SMT solution were carried out for 3 weeks, and different parameters were monitored, especially total organic carbon (TOC) and SMT concentrations. high-performance liquid chromatography results revealed that the target molecule was not assimilated by activated sludge. However, and confirming the improvement previously observed for the biological oxygen demand/chemical oxygen demand (BOD5/COD) ratio, from 0.08 before electrolysis to 0.58 after electrolysis, a pretreatment step in oxidation at 1.6 V/SCE led to a fast decrease of TOC during the subsequent biological treatment, since the mineralization yields increased from 10% for a non-pretreated SMT solution to 76.6% after electrolysis in oxidation (1.6 V/SCE), confirming the efficiency of coupling the electro-oxidation process with a biological treatment for the mineralization of SMT. Moreover, when the electrolysis was performed at 1 V/SCE, no biodegradation was observed, underlining the importance of the electrochemical pretreatment.


Electrochimica Acta | 1994

Electroreduction of α and β meso-nitrodeuteroporphyrins in a flow cell: preparation of meso-aminodeuteroporphyrins and meso-hydroxylaminodeuteroporphyrins

Claude Moinet; Marie Autret; Didier Floner; M. Le Plouzennec; Gérard Simonneaux

Polarograms of a mixture of α and β meso-nitrodeuteroporphyrins (Ia and b) in methanol containing sulphuric acid, show several waves corresponding to the reduction of nitrogroup and porphyrin ring. On the time scale of cyclic voltammetry, hydroxylamino and nitroso derivatives can be observed. The electrosyntheses of α and β meso-hydroxylaminodeuteroporphyrins (IIa and b) and α and β meso-aminodeuteroporphyrins (IIIa and b) are carried out in a flow cell with a porous cathode. Disproportionation of hydroxylamino derivatives occurs in acid medium and limits the yield. The electrosynthesis of α and β meso-nitrosodeuteroporphyrins in a “redox” cell with two consecutive porous electrodes of opposite polarities failed.

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Abdeltif Amrane

École Normale Supérieure

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Olivier Lavastre

Centre national de la recherche scientifique

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Hayet Djelal

École Normale Supérieure

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