Contribution a l'etude de l'ultrafiltration : caracterisation des membranes, etude de la couche de polarisation

SIGLECNRS TD Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Effect of physico-chemical parameters on biohydrogen production and growth characteristics by batch culture of Rhodobacter sphaeroides CIP 60.6

In this paper, Rhodobacter sphaeroides CIP 60.6 strain was newly used for the biohydrogen production in a perfectly shaken column photobioreactor, grown in batch culture under anaerobic and illumination conditions, to investigate the effects of some physico-chemical parameters in microbial hydrogen photofermentation. Luedeking-Piret model was considered for the data fitting to find out the mode of hydrogen generation and the relationship between the cell growth and hydrogen production. The results show that, both growth cells and resting cells can produce hydrogen at light intensities greater or equal to 2500 lux, however, at the weak intensities hydrogen is a metabolite associated to growth. Growth rate and hydrogen production rate increase with the increasing of light intensity. Moreover, hydrogen production rate become higher in stationary phase than that in logarithmic phase, with the enhancement of light intensity. Maximum hydrogen production rate obtained was 39.88 ± 0.14 ml/l/h, at the optimal conditions (4500-8500 lux). Modified Gompertz equation was applied for the data fitting to verify the accuracy and the agreement of the model with experimental results. It is revealed that, in the modified Gompertz equation, the lag time represents time for which hydrogen production becomes maximal, not the beginning time of hydrogen production. The stop of stirring reduced hydrogen production rate and created unstable hydrogen production in reactor. The pH ranges of 7.5 ± 0.1 were the favorable pH for hydrogen production.Biohydrogen production rate Rhodobacter sphaeroides Photofermentation Light intensity Data fitting

Mechanism of phenol adsorption onto electro-activated carbon granules

The main purpose of this paper is to determine the mechanisms which govern the adsorption of the phenol onto electro-activated carbon granules. This new activation technique allowed an increase of the performance of the adsorbent. Two models were utilised to understand the improvement in the performance of electroactivated carbon granules. The first, a simple external resistance model based on film resistance, gave acceptable predictions, with an error of less than 15%, between the theoretical results and experimental data independent of the activation potential and phenol initial concentration. The second linear model, based on diffusion phenomena, was more representative in describing the experiment than the first model. It was observed that the electro-activation method did not change the mechanism which governs phenol adsorption onto granular carbon. Indeed, the same mathematical model based on diffusion phenomena made it possible to predict with a very low error (less than 5%) the experimental data obtained for the favourable activation potential, without activation potential and with an unfavourable activation potential. The electro-activation technique makes it possible to increase the number of active sites that improve the performance of the electro-activated granular carbon compared with conventional granular activated carbon

Electro-Activation of Granular Carbon from Olive Mill Solid Residue

A technique for activation of granualr activated carbon (GAC) is presented based on the electrochemical method. In this study, we investigated the effectiveness of the electroactivated GAC in removing phenol from water and determine the optimum conditions for activation. Electroactivation on the GAC appears to be an interesting technique, it requires a short eletro-activation time T=30 min and an optimum potential ranging from +200 mV/SCE to 400 mV/SCE. Phenol adsorption isotherms gave a limiting adsorption capacity Qm dependent on the applied potential, which at potential E=+300 mV/SCE was improved by about 55 %, giving Qm=75 mg phenol g-1 GAC

Enzymatic degradation and bioactivity evaluation of C-6 oxidized chitosan

International audienceC-6 oxidized chitosan was produced from chitosan by performing selective oxidation with NaOCl andNaBr using 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) as catalyst. Endocellulase, Celluclast1.5 L, Glucanex®, Macerozyme R-10, hyaluronidase, hyaluronate lyase, red scorpionfish chitinase, glu-curonan lyase and a protein mix from Trichoderma reesei were used to degrade the C-6 oxidized chitosan.Glucanex®, the crude extract from T. reesei IHEM 4122 and Macerozyme R-10 validated the enzymaticdegradation through final hydrolysis yields of the derivative respectively close to 36.4, 20.3 and 12.9%(w/w). The best initial reaction velocity (2.41 U/mL) was observed for Glucanex®. The antileishmanialactivity of the derivative was evaluated against Leishmania infantum LIPA 137. The antibacterial activitiesagainst Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 were also tested. Resultsshowed an antileishmanial activity (IC50: 125 g/mL) of the obtained derivatives against L. infantum LIPA137

Enzymatic degradation and bioactivity evaluation of C-6 oxidized chitosan

International audienceC-6 oxidized chitosan was produced from chitosan by performing selective oxidation with NaOCl andNaBr using 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) as catalyst. Endocellulase, Celluclast1.5 L, Glucanex®, Macerozyme R-10, hyaluronidase, hyaluronate lyase, red scorpionfish chitinase, glu-curonan lyase and a protein mix from Trichoderma reesei were used to degrade the C-6 oxidized chitosan.Glucanex®, the crude extract from T. reesei IHEM 4122 and Macerozyme R-10 validated the enzymaticdegradation through final hydrolysis yields of the derivative respectively close to 36.4, 20.3 and 12.9%(w/w). The best initial reaction velocity (2.41 U/mL) was observed for Glucanex®. The antileishmanialactivity of the derivative was evaluated against Leishmania infantum LIPA 137. The antibacterial activitiesagainst Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 were also tested. Resultsshowed an antileishmanial activity (IC50: 125 g/mL) of the obtained derivatives against L. infantum LIPA137