Non linear modelisation of dyes removal from aqueous solution by using sorption onto Luffa cylindrica fibers

The biosorption of indigo carmine (IC) and methylene blue (MB) using a lingo-cellulosic fiber: Luffa cylindrical was carried out in this study. It was shown in this work, that biosorption capacity of dyes increase with increase of initial dyes concentrations and mass of biomass and to decrease with the raise of salt and temperature. Optimal parameters of the biosorption of dyes onto Luffa cylindrica were obtained after 150 min and pH 10 for MB and 525 min and pH 2 for IC. The experimental equilibrium data were studied employing the isotherms of Langmuir, Freundlich, Jovanovic, Temkin, Redlich–Peterson, Toth, Sips, and Brouers–Sotolongo. The experimental data fitted very well with the Bouers-Sotolongo isotherm for MB and the Toth isotherm for IC. Concerning IC, the value of maximum biosorption capacity (Qm = 6.876 mg/g) was close to the experimental value (Qm = 6.874 mg/g), and the correlation coefficient (R2) was 0.996. While for MB, the value of maximum biosorption capacity (Qm = 13.849 mg/g) was close to the experimental value (Qm = 13.900 mg/g), and the correlation coefficient (R2) was 0.992. In order to study the biosorption kinetics, four kinetics models such as pseudo-first order, pseudo-second order, Elovich and Brouers-Sotolongo were studied. The Brouers-Sotolongo (2,α) fractal  model appears to be the best model to fit the experimental data.  

Leiomyome agressif naso-sinusien : a propos d’un cas et revue de la litterature

Introduction : Les léiomyomes sont des tumeurs bénignes issues des fibres musculaires lisses. La localisation au niveau des cavités nasosinusiennes est très rare.Cas clinique : Il s’agit d’une patiente âgée de 59 ans, qui a consulté pour obstruction nasale et épistaxis gauches. L’endoscopie nasale a montré une formation comblant totalement la fosse nasale gauche. L’imagerie (TDM, IRM) a objectivé un volumineux processus expansif tissulaire naso-ethmoïdo-maxillaire, avec extension intra-orbitaire et endocrânienne. La biopsie confirmé qu’il s’agit d’un léiomyome à localisation nasosinusienne. La patiente a été opérée par voie paralatéronasale élargie. Elle a eu une exérèse tumorale complète et une reconstruction de la perte de substance osseuse par autogreffe. Les suites opératoires étaient simples. Aucune récidive n’a été notée après un recul de 1 an.Conclusion : La localisation nasosinusienne du léiomyome est très rare. L’imagerie est indispensable dans le cadre du bilan d’extension loco-régional. Seul une exérèse chirurgicale complète permettra d’éviter toute récidive aussi bien à court qu’à long terme.Mots-clés : léiomyome, fosses nasales, sinus, tomodensitométrie, imagerie par résonance magnétique, chirurgie sinusienneIntroduction: Leiomyomas are benign tumors arising from smooth muscle fibers. The location at the sinonasal cavities is very rare.Case report: This is a female patient aged 59, who consulted for left nasal obstruction and epistaxis. Nasal endoscopy showed a tumor completely filling the left nasal cavity. Imaging (CT, MRI) has objectified a large expansive tissularnaso-maxillary-ethmoidal process with intraorbital and intracranial extension. The biopsy confirmed that this was a leiomyoma with sinonasal localization. The patient was operated by extended paralatéronasale approach. She had a complete tumor resection and reconstruction of the bone defect with autograft. The postoperative course was uneventful. No recurrence was observed after a follow-up period of 1 year.Conclusion: The sinonasal location of leiomyoma is very rare. Imaging is essential for locoregional staging. Only a complete surgical resection will prevent any recurrence both in short and long term.Keywords : leiomyoma, nasal fossae, sinus, computed tomography, magnetic resonance imaging, sinusal surger

Selective and low temperature transition metal intercalation in layered tellurides

Layered materials embrace rich intercalation reactions to accommodate high concentrations of foreign species within their structures, and find many applications spanning from energy storage, ion exchange to secondary batteries. Light alkali metals are generally most easily intercalated due to their light mass, high charge/volume ratio and in many cases strong reducing properties. An evolving area of materials chemistry, however, is to capture metals selectively, which is of technological and environmental significance but rather unexplored. Here we show that the layered telluride T2PTe2 (T=Ti, Zr) displays exclusive insertion of transition metals (for example, Cd, Zn) as opposed to alkali cations, with tetrahedral coordination preference to tellurium. Interestingly, the intercalation reactions proceed in solid state and at surprisingly low temperatures (for example, 80?°C for cadmium in Ti2PTe2). The current method of controlling selectivity provides opportunities in the search for new materials for various applications that used to be possible only in a liquid

Removal of cationic pollutants from water by xanthated corn cob: optimization, kinetics, thermodynamics, and prediction of purification process

The removal of Cr(III) ions and methylene blue (MB) from aqueous solutions by xanthated corn cob (xCC) in batch conditions was investigated. The sorption capacity of xCC strongly depended of the pH, and increase when the pH rises. The kinetics was well fitted by pseudo-second order and Chrastil’s model. Sorption of Cr(III) ions and MB on xCC was rapid during the first 20 min of contact time and, thereafter, the biosorption rate decrease gradually until reaching equilibrium. The maximum sorption capacity of 17.13 and 83.89 mg g-1 for Cr(III) ions and MB, respectively was obtained at 40 °C, pH 5 and sorbent dose 4 g dm-3 for removal of Cr(III) ions and 1 g dm-3 for removal of MB. The prediction of purification process was successfully carried out and the verification of theoretically calculated amounts of sorbent was confirmed by using packed-bed column laboratory system with recirculation of the aqueous phase. The wastewater from chrome plating industry was successfully purified, i.e. after 40 min concentration of Cr(III) ions was decreased lower than 0.1 mg dm-3. Also, removal of MB from the river water was successfully carried out and after 40 min removal efficiency was about 94 %

Comparison of different wind farm layouts for a 25 MW project in the south west of Algeria

The object of this work is to evaluate and compute the power potential of the KABERTEN site and to make the rigorous choice among different placements of wind turbines in order to decrease the wake effect and improve the power efficiency. Three proposals of wind farm layouts where all the turbines are faced to the prevailing wind have been used in the simulations. The results for individual and global energy yield as well as wake loss have been obtained and plotted. The wind Atlas Application Program (WASP) software of the Danish RISO laboratory is used in the study as a simulation tool to evaluate potential of the chosen site and to determine the best wind farm layout for a 25 MW projec

Maximum power point tracker of wind energy conversion system

In this paper, a simple control strategy for an optimal extraction of output power from grid connected variable speed wind energy conversion system (WECS) is presented. The system consists of a variable speed wind turbine coupled to a permanent magnet synchronous generator (PMSG) through a gear box, a diode bridge rectifier, a dc-to-dc boost converter and a current controlled voltage source inverter. The maximum power point tracker (MPPT) extracts maximum power from the wind turbine from cut-in to rated wind velocity by sensing only dc link power. The MPPT step and search algorithm in addition to the DCeDC and DCeAC converters PWM controllers are simulated using MATLAB-SIMULINK software. The obtained simulation results show that the objectives of extracting maximum power from the wind and delivering it correctly to the grid are reache

Using a DFIG based wind turbine for grid current harmonics filtering

In this paper a variable speed doubly fed induction generator (DFIG) based wind energy conversion system (WECS) is employed for simultaneous power generation and grid harmonic current filtering. WECS active and reactive powers are controlled using vector control strategy. An improved harmonic isolator in the time domain, based on a new high selective signal detector or filter (HSF) has been used. Since the polluting currents contain direct and reverse harmonics of (6k +/- 1) order, the HSF can be used to isolate one particular harmonic or the whole harmonic components. The compensation technique of the whole harmonic components of the grid current is chosen. The rotor side converter (RSC) control structure has been modified in order to include the filtering task. Simulation for a 3 MW WECS with DFIG at two different wind speeds (8 m/s and 12 m/s) has been performed. Results showed that in addition to power generation, grid current harmonics filtering action is achieved by the WECS and a decrease by 4% of the total harmonic distortion is obtained