29 research outputs found
Set up of a microbial fuel cell for the treatment of a garden compost leachate: Impact of the external polarizing electric resistance upon the chemical oxygen demand removal
No full textInternational audienceMicrobial fuel cells (MFCs) are new and growing renewable energy devices. They transform chemical products into electricity with the help of microorganisms (enzyms, bacteria, microbes, etc…) acting as biocatalysts. They are nowadays displaying technological development, since they concomitant simultaneously the wastewater treatment and the electric power generation. These two novelties incite researchers in the field, the utilization of this propising technology. As a matter of fact, a bioelectrochemical has been elaborated and set up for garden compost leachate treatment. Following a previous study on the microbial anode formed from wastewater under the application of an electric potential either positive or negative by using chronoamperomtry, we propose in this work, the simple method of connecting the two electrodes (anode and cathode) by an electric resistance, to flow a current. The impact of the polarizing electric load on the achievement of the MFC has therefore been studied. Moreover, the chemical oxygen demand (COD) removal for the MFC running for 7 days has been also investigated. It decreased and showed simultaneously an increase in the cell voltage. Thus, the effect of the external load on the current and power generation, as well as on the pollutant removal, have been studied by modifying each time the external load. The external polarizing resistance (EPR) was increased from 1 to 10 kΩ, to assess the pollutant decay of the organic matter contained in the wastes. As a result of this, the voltage was increased, whilst the current was decreased, with increasing values of the EPR. The results have been discussed with respect to the type and the predominant microorganisms (Electrogenic/Fermentative) being involved during the generation of the electric current. This new technology is very promising to converting wastes into electricity by offering in the same time the way to cleaning up the polluted environment
Ionic Exchange Membrane Used as Separator in Methanol Fuel Cell: An Electrochemical Characterization Using Hydro-Organic Solution
No full textElaboration of novel biocomposite hydrogel polymers made of alginate and sepiolite and endowed with enhanced properties
No full textInternational audienceNowadays growing attention is given to the design and development of novel interpenetrating polymer networks (IPN) from the combination of hydrogel polymers loaded with natural clay. In this work, we used the eco-friendly IPN strategy to develop novel hydrogel biocomposite beads, made of alginate (ALG), with improved clay dispersion, higher pH sensitivity, better stretchability and swellability, together with enhanced regenerability properties and delayed biodegradability. Fibrous clay, namely, sodium sepiolite (NaS), was loaded into alginate simple biocomposite network (SBN) beads, via manual co-grinding mixture/encapsulation method, at different sepiolite loads. Alginate double biocomposite network (DBN) beads were also prepared at different sepiolite loads, via the diffusion of acrylamide monomers (AAM) inside alginate single biocomposite network (SBN) beads, followed by external and in situ free radical polymerization of AAM into polyacrylamide (pAAM), using ammonium persulfate (APS) as polymerization initiator and N,Nmethylenebisacrylamide (Bis) as covalent crosslinker agent. The as-elaborated SBN and DBN beads were then characterized by digital camera recording, XRD analysis, ATR-FTIR characterization and SEM observation. FTIR results showed that NaS and pAAM were successfully incorporated into DBN beads, while partially exfoliated morphology was obtained with XRD analysis, which revealed the enhancement of fibrous clay dispersion, even at relatively high sepiolite loads. Besides, SEM microscopy confirmed the porous spongious nature of DBN beads. The properties of the as-elaborated SBN and DBN beads were also evaluated by test touching, swelling rate measurements, adsorption/desorption experiments and biodegradability evaluation. DBN beads properties were always found enhanced in comparison with those of SBN beads. This suggests that the synergetic effect between IPN and biocomposite structure improves the stretchability of the DBN beads, their stability in water whatever the pH and their swelling behavior (up to 2000 g/g adsorbed water after 110 min, which was nevertheless found dependent on the pH and on sepiolite load). Moreover, DBN beads displayed enhanced adsorption/desorption properties Extended author information available on the last page of the article Polymer Bulletin toward methylene blue (MB) dye (no reduction in MB adsorption capacity after 5 cycles), very good regenerability (ethanol being used as effective eluting agent) and delayed biodegradability (complete degradation only after 8 days in the presence of sepiolite). In summary, this work showed an interesting and safe IPN/biocomposite approach to develop high-performance alginate biocomposite polymers as a promising system toward their use in eco-friendly processes.</div
Design of a Microbial Fuel Cell Used as a Biosensor of Pollution Emitted by Oxidized Organic Matter
No full textProduction of Bio-Energy Using Biological Fuel Cell: Application to Electro-Dialysis for Recovery of Heavy Metal Traces from Treated Wastewater
No full textInternational audienceBiological Fuel Cell (BFC) is a device that converts chemical energy into electric energy by using a biological catalyst such as enzyme, microbe, bacteria, etc. …, and a fuel. Although enzymes and microorganisms are highly efficient biocat-alysts. The microbial desalination cell (MDC) a newly developed technology, integrated the Microbial Fuel Cell (MFC) process and electro-dialysis (ED) for wastewater treatment, water desalination and production of renewable energy. The cell developed herein, was composed of two compartments: anode and cathode compartments separated by a cation exchange membrane. The biocatalyst was either on the electrode and suspended in solution. The anode was in general a carbon-based electrode, while the cathode was stainless steel plate. The connection between the two electrodes via an electrical resistance allowed the flow of electrons from the anode to the cathode through the external circuit. This flow was compensated by the flow of ions through the internal circuit. Though it was relatively weak, the produced bio-energy was always enough to feed low energy devices. We have demonstrated herein the potential energy for the treatment of a wastewater. We have proved the degradation of organic matter using the bio-film, by measuring the abatement of Chemical Oxygen Demand (COD). Besides, we have eliminated the residual heavy metal traces using by electro-dialysis. In effect, we used the bio-energy produced by the (BFC) to feed the three-compartment electro-dialysis cell (EDC). Compared to electro-dialysis, our results proved the possibility to recover metal traces at approximately the same rate of abatement, using this novel biological device
New synthesized bismuth-based pyrochlore compounds Bi1.5-xMxSb1.5-xM'xZnO7 (M= Fe; M'=Fe, Cr) (x=0.0; 0.10; 0.15): A structural study.
No full textAbstract New limited pyrochlore solid solutions of formula Bi1.5-xMxSb1.5-xM'xZnO7 (M= Fe; M'=Fe, Cr) (x=0; 0.10; 0.15) are prepared from simple oxides at 1080°C by using the ceramic method. All the crystal phases are indexed in the cubic system (space group; No.227). Rietveld refinement method of the Bi1.5Sb1.5ZnO7 (x=0) compounds using powder XRD analysis confirms an overall A2B2O7 cubic pyrochlore structure according to B i 1 . 5 3 + Z n 0 . 5 2 + S b 1 . 5 5 + Z n 0 . 5 2 + O 7 formula with 10.44425(3) Å and F d 3 ¯ m space group. The substitution of Bi(III) and Sb(V) by Fe(III) and Cr(III) in the Bi1.5Sb1.5ZnO7 phase shows the appearance of solid solutions limited to x=0.15. The variation of the cell’s parameter is recorded to the element’s ionic radii. The paramagnetic character is observed in all substituted compounds. The measurements of the electrical conductivity as a function of the temperature, make evidence of the semi-conductive property. Whilst, the magnetic susceptibility satisfies the modified Curie Weiss (CW) and shows the magnetic behavior due to the magnetic moments of the iron and chromium ions being involved in the synthesis of the compounds. Besides, the UV-Visible reflectance displays light absorption in the visible domain
Fabrication and Performance of a Microbial Fuel Cell: Utilization of Modified Nafion Membrane with Carbon Powder as Separator and Bio-Anode
No full textInternational audienceA Microbial Fuel Cell (MFC) was conceived by using garden soil as a source to culture. It was then utilized as a bio-catalyst to decompose waste organic matter, reduce pollution from the soil, and produce energies. The MFC was composed of a bio-anode inoculated with a mixture of garden compost leachate and an abiotic stainless steel cathode. Besides, the bio-anode consisted of a Nafion membrane modified with carbon. The microorganisms agglomerated under polarization and formed electroactive bio-film onto bio-anode. In the preliminary test of MFC, potassium hexacyanoferrate has been utilized as catholyte, to enhance the reduction of proton and electrons resulting in a higher voltage. However, this electrolyte is toxic and oxidized rapidly, thus substituted by the hydrochloric acid. The results showed that the MFC with modified Nafion, gave relatively high current-density 379 mA/m2 in two days, whereas the conventional biofuel cell without modification attained the current-density 292 mA/m2 in four days. Nevertheless, both cells yielded almost the same current density of 20 mA/m2 during 60 days. Although it has been used for a long time, the modified Nafion has not been corroded and preserved its physicochemical properties
Etude du repiquage du biofilm électroactif sur une électrode de feutre de carbone. Caractérisation par voltamétrie cyclique et spectroscopie d’impédance,
No full textInternational audienc
A new technical for solving a weakly singular integro-differential equations
No full textAbstractIn this work, we transform a weakly singular integro-differential equations with logarithmic kernel to singular integral equations of Cauchy type and we prove by regularization the existence and uniqueness of the solution of this equations. Numerical examples illustrate the effectiveness of this new technical methods
THE THEORY OF LITERARY GENRES IN GEORGE LUKACS (HUNGARY)
No full textIn spite of his high reputation among the contemporary intellectual audience, Lukacs' work is still perceived and treated reductively in parts, especially with respect to his literary theory and criticism. Believing that Lukacs' views particularly in this sphere of aesthetic form an evolving whole, this study seeks to construct the most fundamental principles on which he bases his genre theory. This perspective was chosen because, like many critics, I regard genre theory as the formative principle of literary theory as a whole.Mostly through descriptive method, this study exposes and explains the differences that Lukacs directly or indirectly makes between modes (the historically universal categories of the genre system), and genres (the variables that represent the more concrete changes in the historical process as aesthetically reflected in literary forms).Throughout his career, Lukacs established his genre theory on one central category, that of totality. The modes represent the most fundamental types of totality: totality of objects for epic, totality of movement for drama, and totality of the lyrical moment or the subjective for lyric.The genres, on the other hand, are the more concrete forms in which the modes, and thus the totalities, aesthetically objectify themselves. They are, in other words, the aesthetic forms of particular historical moments, such as the epic genre for early Greek society or the novel for the bourgeois society.Although it contains some weaknesses, Lukacs' genre theory does form a whole that is deep, rich, insightful, and very useful in understanding the problems of genre, especially from an historical perspective.Source: Dissertation Abstracts International, Volume: 46-02, Section: A, page: 4150.Ph.D. American University 1984.Englis
