Extraction du complexe (&#87331P2W17O61Fe)7-, par membrane liquide emulsionnee

Extraction of complex (∝1P2W17O61Fe)7- by liquid surfactantmembrane The extraction of a Dawson-type heteropolyanion (∝1P2W17O61Fe) 7- was carried out by liquid surfactant membrane using (SPAN80) as surfactantand (TIBA) as extractant, internal phase used (NH4)2CO3. The extraction efficiency is 90 %. Then in order to regenerate the membrane, the stripping efficiency was given according to the concentration of the internal phase, the stripping efficiency is 76 % was obtained for (NH4)2CO3 concentration 1 M

Synthèse de HCs5P2W18O62.16H2O et application à l’adsorption de la matière organique: bleu de méthylène

La présente étude porte sur l'adsorption d'un colorant, le bleu de méthylène (BM), par un hétéropolyanion saturé de type Dawson, substitué par le césium HCs5P2W18O62.16H2O. La première partie a trait à la synthèse et à la caractérisation de l'adsorbant. La dernière partie est consacrée à l'étude de l'adsorption et à l'optimisation des paramètres qui la gouvernent ainsi qu'à la régénération de l'adsorbant. Le rendement optimal de l'adsorption est de 88% pour une concentration en BM de 25 mg/L et une masse d’adsorbat de 0.25g. Le rendement de la régénération est de 98% pour une température de 80°C.Mots clés: Adsorption - Bleu de méthylène - Hétéropolyanion - Caractérisation spectroscopique - DawsonThe adsorption of a dye, the deals with methylene blue, by a Dawson type heteropolyanion HCs5P2W18O62.16H2O, substituted by caesium, was investigated. The first part is for the synthesis and characterization of the adsorbent. The experimental parameters affecting the adsorption were then optimized. The regeneration of the adsorbent was finally studied. The optimal yield found was 88% for a MB concentration of 25 mg/L and an adsorbent mass of 0.25g. The yield of the regeneration was 98%, at 80°C.Keywords: Adsorption - Methylene blue - Heteropolyanion - Dawson - Spectroscopic characterizatio

Synthesis, characterization of cesium and cobalt substituted wells–Dawson heteropolyoxotungstates salts and their photocatalytic applications

Heteropoly compounds in the solid state are ionic crystals (sometimes amorphous) consisting of large polyanions, cations, water of crystallization, and other molecules. Heteropolyacids (HPAs) have several advantages as catalysts. On the one hand, they have a very strong Brønsted acidity, especially the cobalt and cesium salts; on the other hand they are exhibiting fast reversible multielectron redox transformations under mild conditions. The cobalt and cesium salts of wells–Dawson HPAs were synthesized and characterized using elemental analysis and spectroscopic techniques (31P-NMR, FT-IR). The wells–Dawson anions possess the ability to accept or release electrons through an external potential or upon exposure to UV radiation (photochemical reactions). The catalytic tests of these salts were investigated on phenol degradation where the UV photodegradation of acidified aqueous solutions (pH = 2) were studied in a batch photoreactor under ambient temperature and continuous circulation of phenol solution. The results reveal high catalytic activity for two HPAs, the best catalyst is the salt of cesium; where the presence of cesium improves significantly both the photcatalytic activity and the selectivity to oxalic acid