Le charbon actif élaboré à partir de biomasses lignocellulosiques est une bonne voie de valorisation de déchets, vue ses applications. Ce travail porte sur l'élaboration du charbon actif à partir de Balanites aegyptiaca par activation chimique à l'acide ortho phosphorique, son application pour éliminer le chrome VI en solution. La concentration de l'acide, le temps d'imprégnation, la température de pyrolyse et le palier d'isotherme ont été variés. La caractérisation a porté sur la détermination des indices d'iode et de bleu de méthylène, des fonctions de surface et de pH au point de charge nulle (pH PCN). Le temps de contact, le pH du milieu, la masse de l'adsorbant et la concentration initiale de la solution ont été variés pour l'élimination du chrome. Les meilleurs indices d'iode et de bleu de méthylène obtenus sont : 989,86 mg/g et 613,17 mg/g respectivement. Les fonctions à la surface des charbons actifs sont de nature acide et leur pH PCN inférieur à 7. Le rendement d'élimination du chrome varie de 81,64% à 98,77% dans les conditions : concentration initiale (70 mg/L), pH = 2, masse (80 mg) et temps (2 h). A titre de comparaison, le charbon actif commercial de marque KGA a donné un taux de rabattement en chrome de 91,49%.

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Landfill leachate is a great danger to the environment. In order to answer the questions of a healthy environment, the leachates produced at the Niamey 2000 landfill site were characterized. Samples were taken at various points around 1 and 4 o'clock in the landfill. The parameters determined are: temperature, pH, electrical conductivity, dissolved oxygen, suspended solids, turbidity, cations (sodium, potassium, calcium, magnesium and ammonium), anions (sulfate, chloride, nitrate) , ortho-phosphates and bicarbonate), metallic trace elements (iron, copper, chromium, cadmium, nickel, cobalt and zinc) by a Hach DR 3800 spectrophotometer, BOD5 and COD. The results of the analyzes show that the leachates produced at the Niamey 2000 landfill are basic (minimum pH 7.6), highly charged with suspended matter (590mg / L), very turbid (297NTU) and highly polluted (dissolved oxygen less than 3mg / L). The mineral pollution is characterized by a high average electrical conductivity of 2441.5 μS / cm, a high concentration of chlorine (1276.5 mg / L) and orthophosphates (3.31 mg / L). The organic load is translated by an average COD of 2248mgO2 / L and an average BOD5 of 530mgO2 / L. These leachates are characterized by high concentrations of iron, zinc, cadmium and copper which are respectively in mg / L of 9.26; 8.75; 0.19 and 2.3. Elements such as nickel and chromium are present at levels below the limits set by the Nigerian release standard.

This study focuses on the liquid-liquid extraction of uranium by anionic extractants of Alamine 336 and Aliquat 336. The objective of this study is to determine the parameters allowing the optimization of the extraction percentage of uranium, and other metals such as molybdenum, zirconium and vanadium. The extraction kinetics of uranium is achieved in 2 minutes. Sulfuric acid solutions are the media per excellence when using Alamine 336 as extractant. However,with Aliquat 336, it is orthophosphoric acid. Uranium is extracted at 99% in a single contact from the ratio: organic phase over aqueous phase (O/A) equals 1. The extraction of uranium with Alamine 336 depends on the initial pH of the aqueous phase as well as the Alamine 336 concentration. Alamine 336 tends to release the uranium and the extracted zirconium until the 3 rd contact to the benefit of the molybdenum due to the natural occurrence of 𝐶𝑙−,𝑁𝑂3 − and 𝐹 − ions in the uranium-bearing solutions which have the tendency of breaking the anion complexes. Vanadium, which is not extracted by Alamine 336 and Aliquat 336, can, in the hydrodynamic conditions of this work, be extracted by increasing the redox potential to 800 mV and pH ≥ 1.

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