5 research outputs found
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 âcoacervate extractionâ 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 (Ï). 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 ÏC. 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 itâs 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.Lâobjectif de ce mĂ©moire est le dĂ©veloppement dâun rĂ©fractomĂštre basĂ© sur un rĂ©sonateur optique pour la mesure de lâindice de rĂ©fraction de gaz, notamment lâair, avec une incertitude relative infĂ©rieure Ă 10-8, au voisinage de la pression atmosphĂ©rique. On prĂ©sente ici lâensemble des travaux effectuĂ©s pendant la durĂ©e du projet.Il a tout dâabord fallu caractĂ©riser le rĂ©sonateur optique (Fabry Perot) : mesures de frĂ©quences de rĂ©sonance, de lâintervalle spectral libre, du coefficient de dilatation thermique, du coefficient de dĂ©formation par unitĂ© de pression en utilisant lâhĂ©lium. Un bilan dâincertitudes provisoire de cette caractĂ©risation est favorable Ă la poursuite des mesures dâindice Ă mieux que 10-8.Le rĂ©fractomĂštre a pu ĂȘtre testĂ© via la mesure de la rĂ©fractivitĂ© molaire de lâazote pur Ă 532 nm. Le rĂ©fractomĂštre a Ă©tĂ© capable de mesurer lâindice de gaz purs Ă lâĂ©chelle de 10-8 (en utilisant lâhĂ©lium) et a montrĂ© une excellente rĂ©solution (<10-9). Lâindice de lâair dans les conditions ambiantes (laboratoire) a pu ĂȘtre mesurĂ© et comparĂ© Ă lâindice donnĂ© par les formules dâEdlĂ©n. LâĂ©cart entre les deux valeurs est infĂ©rieur Ă lâincertitude associĂ©e aux formules dâEdlĂ©n.Pour diminuer lâincertitude sur la mesure de lâindice de lâair afin dâĂȘtre infĂ©rieure Ă 10-8, un effort doit ĂȘtre rĂ©alisĂ© dans la connaissance du phĂ©nomĂšne de pollution (impuretĂ© du gaz, dĂ©pĂŽt de couches dâeau sur les miroirsâŠ) et dans lâamĂ©lioration de lâĂ©tanchĂ©itĂ© de lâenceinte