Extraction of humic acid by coacervate: Investigation of direct and back processes

The two aqueous phases extraction process is widely used in environmental clean up of industrial effluents and fine chemical products for their reuse. This process can be made by cloud point of polyethoxylated alcohols and micellar solubilization phenomenon. It is commonly called “coacervate extraction” and is used, in our case, for humic acid extraction from aqueous solution at 100 mg/L. The surfactants used are alcohol polyethoxylate and alkylphenol polyethoxylate. Phase diagrams of binary water/surfactant and pseudo-binary are plotted. The extraction results are expressed by the following responses: percentage of solute extracted, E (%), residual concentrations of solute and surfactant in dilute phase (Xs,w, and Xt,w respectively) and volume fraction of coacervate at equilibrium (ϕ). For each parameter, the experimental results are fitted to empirical equations in three dimensions. The aim of this study is to find out the best compromise between E and ϕC. The comparison between experimental and calculated values allows models validation. Sodium sulfate, cetyltrimethylammonium bromide (CTAB) addition and pH effect are also studied. Finally, the possibility of recycling the surfactant has been proved

A Novel Algorithm to Estimate Closely Spaced Source DOA

In order to improve resolution and direction of arrival (DOA) estimation of two closely spaced sources, in context of array processing, a new algorithm is presented. However, the proposed algorithm combines both spatial sampling technic to widen the resolution and a high resolution method which is the Multiple Signal Classification (MUSIC) to estimate the DOA of two closely spaced sources impinging on the far-field of Uniform Linear Array (ULA). Simulations examples are discussed to demonstrate the performance and the effectiveness of the proposed approach (referred as Spatial sampling MUSIC SS-MUSIC) compared to the classical MUSIC method when it’s used alone in this context

Cationic Dye Removal from Aqueous Solutions Using Ionic Liquid and Nonionic Surfactant-Ionic Liquid Systems: A Comparative Study Based upon Experimental Design

In order to separate methylene blue from aqueous solution, a novel method based upon liquid-liquid extraction, using a nonionic surfactant-ionic liquid system as extracting phase, was investigated. A comparative study was carried out with the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, known as [C4mim]PF6. By using the nonionic surfactant-ionic liquid system, the extraction efficiency could reach 97.8%, indicating that the addition of nonionic surfactant (Triton X-114) significantly improves the extraction of methylene blue. Under optimal conditions, the dye concentration in the effluent showed an almost 50-fold reduction. However, the extraction extent of methylene blue was found to be low at low pH values, and in the presence of K2CO3, which may be useful for surfactant-ionic liquid system regeneration

Réfractométrie absolue basée sur l'hélium

The aim of this thesis is the development of a refractometer based on an optical resonator for the measurement of refractive index of gases, including air, with a relative uncertainty of less than 10-8, in the vicinity of atmospheric pressure. We presente here all work performed throughout the duration of the project.Firstly, it was necessary to characterize the optical resonator (Fabry-Perot): measurements of resonance frequencies, of the free spectral range, of the coefficient of thermal expansion, coefficient of distorsion per unit of pressure using helium. A preliminary uncertainty budget of this characterization is supported further index measurements to better than 10-8. The refractometer has been tested by measuring the molar refractivity of pure nitrogen at 532 nm. It was able to measure the index of pure gases wide 10-8 (using helium) and displayed excellent resolution (<10-9). The index of air at ambient conditions (laboratory) could be measured and compared to the index given by Edlen. The difference between the two values is less than the uncertainty associated with Edlen formulas.To reduce the uncertainty in the measurement of the index of air below 10-8, efforts should be made to understanding better the phenomenon of pollution (impurity gas, depositing layers of water mirrors ...) and as well as to improve the seal of the enclosure.L’objectif de ce mémoire est le développement d’un réfractomètre basé sur un résonateur optique pour la mesure de l’indice de réfraction de gaz, notamment l’air, avec une incertitude relative inférieure à 10-8, au voisinage de la pression atmosphérique. On présente ici l’ensemble des travaux effectués pendant la durée du projet.Il a tout d’abord fallu caractériser le résonateur optique (Fabry Perot) : mesures de fréquences de résonance, de l’intervalle spectral libre, du coefficient de dilatation thermique, du coefficient de déformation par unité de pression en utilisant l’hélium. Un bilan d’incertitudes provisoire de cette caractérisation est favorable à la poursuite des mesures d’indice à mieux que 10-8.Le réfractomètre a pu être testé via la mesure de la réfractivité molaire de l’azote pur à 532 nm. Le réfractomètre a été capable de mesurer l’indice de gaz purs à l’échelle de 10-8 (en utilisant l’hélium) et a montré une excellente résolution (<10-9). L’indice de l’air dans les conditions ambiantes (laboratoire) a pu être mesuré et comparé à l’indice donné par les formules d’Edlén. L’écart entre les deux valeurs est inférieur à l’incertitude associée aux formules d’Edlén.Pour diminuer l’incertitude sur la mesure de l’indice de l’air afin d’être inférieure à 10-8, un effort doit être réalisé dans la connaissance du phénomène de pollution (impureté du gaz, dépôt de couches d’eau sur les miroirs…) et dans l’amélioration de l’étanchéité de l’enceinte

An investigation on polymer ion exchange membranes used as separators in low-energy microbial fuel cells

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