Étude de l'élimination de bleu de méthylène dans l'eau par le charbon actif commercial CECA40


The removal of methylene blue(BM) through adsorption over the commercial actived charcoal ( CECA 40) was studied in a static batch reactor. At constant pH and temperature the adsorption equilibrium time is equal to 5 hours regardless of the initial concentration of metylene blue (BM). The adsorption in this case follows a Langmuir isotherm of the first type with an ultimate adsorption capacity of about 367,6 mg of methylene blue for each gram of CECA 40. Moreover, we observed no significant influence of temperature on the adsorption equilibrium. The adsorption and the Intraparticular diffusion kinectics were studied. Adsorption is clearly higher in an alcaline environment than in the acid one. This adsorption is further improved by the use of finer granulometry

Preparation and optical characterization of transparent, microporous TiO2 xerogel monoliths

International audienceThis paper focuses on the sol–gel preparation and spectroscopic characterization of transparent and rare earth-doped TiO2 monoliths, for further applications in luminescence. The preparation method was based on a sol–gel technique applied to titanium isopropoxide as the precursor. By controlling the hydrolysis of this precursor by the intermediate of an esterification reaction, and by also controlling the rate of drying, transparent TiO2 xerogel monoliths were obtained at room temperature. The monoliths prepared in this manner were transparent to wavelengths between 400 and 1400 nm. They had a microporous texture, a specific surface area of ≈330m2 g−1 and they were partly X-ray amorphous. After heat treatment at 823K for 6 h in air, the N2 adsorption isotherm analysis indicated that a densification process occurred altogether with a phase transition from partly amorphous to anatase. The X-ray diffraction spectra indicated that the anatase crystals had a size in the range of the nm, while the UV transmission spectra kept the same characteristics as at room temperature

Chemical compositions of the Tunisian Ziziphus jujuba oil

International audienceThirteen fatty acids were identified from the pulps of four Tunisian Ziziphus jujuba ecotypes (Sfax, Choutrana, Mahres and Mandia), using capillary gaseous chromatography method. These oils presented 8.31% to 12.35% of dry weights. Compared to the other ecotypes, Mahres and Choutrana were the richest of the oleic acid. The palmitic acid was the most important compound of the Sfax ecotype. Unsaturated fatty acids ranged from 62.63% to 72.40% of the total fatty acids of each ecotype. So a ratio of the unsaturated/saturated (U/S) varied from 1.68 to 2.37. The beta-sitosterol and the Stigmasterol were identified as major sterols. The beta-sitosterol was the prominent component in the all ecotypes and the highest level (10.65 mg/100g) was noted in Choutrana ecotype. Stigmasterol was more abundant in Sfax (16.12 mg/100g) and Choutrana (4.67 mg/100g) ecotypes. The campesterol sterol was identified only in Sfax and Choutrana ecotypes being more important (2.4 mg/100g) in Choutrana pulps

Adaptation of the revised universal soil loss equation (RUSLE) to soil loss modeling in a semi-arid watershed: a case study from western high atlas, Morocco

Soil loss called also soil erosion is one of the most irreversible natural phenomena that affect the topsoil of Earth’s surface worldwide, as it causes soil fertility reduction, water availability decrease, and initiation of geo-hazards, which leads to negative repercussions on agricultural production, considered the main source of income for most of the autochthonous in the moroccan High Atlas. Due to its climatic and anthropogenic conditions, this region is considered one of the most vulnerable areas to soil erosion in Morocco, with consequential environmental and socioeconomic concerns. This study assesses soil loss in the upstream part of the High Souss watershed in the moroccan western High Atlas, using an integrated analysis of Remote Sensing, GIS, and the Revised Universal Soil Loss Equation (RUSLE). This assessment is based on the integration of different influencing factors: climate, soil erodibility, topography, vegetation cover, and soil conservation practices. Results reveal that the High Souss watershed is exposed to significant erosion, with an average soil loss of 57.27 t/ha/year and an annual erosion amount of 7.3 million tons. This rate is considered to be intensively high in the moroccan context. Moreover, areas subjected to intensive erosion risk are mainly located in the upstream part of the basin, where moderate to steep slope lands are concentrated. The used methodology and results have been compounded to facilitate the analysis of this risk, providing an important basis for government decision-makers, helping the design of meaningful conservation planning programs to reduce soil erosion and conserve natural resources, thus supporting regional development

Study of interaction between chitosan and active carbon in view of optimising composite gels devoted to heal injuries

In order to develop biomaterials useful in reconstructive surgery, mechanism of adsorption of chitosan onto activated carbon has been investigated. Activated carbons have been characterised using SEM, NH3 adsorption and 129Xe NMR spectroscopy. Adsorption of chitosan on activated carbon in acid aqueous solution increases when the degree of acetylation of chitosan decreases. Sterilization does not modify the adsorption capacity of the studied sample of activated carbon

Spatial prediction of groundwater potentiality in large semi‐arid and karstic mountainous region using machine learning models

The drinking and irrigation water scarcity is a major global issue, particularly in arid and semi‐arid zones. In rural areas, groundwater could be used as an alternative and additional water supply source in order to reduce human suffering in terms of water scarcity. In this context, the purpose of the present study is to facilitate groundwater potentiality mapping via spatial‐modelling techniques, individual and ensemble machine‐learning models. Random forest (RF), logistic regression (LR), decision tree (DT) and artificial neural networks (ANNs) are the main algorithms used in this study. The preparation of groundwater potentiality maps was assembled into 11 ensembles of models. Overall, about 374 groundwater springs was identified and inventoried in the mountain area. The spring inventory data was randomly divided into training (75%) and testing (25%) datasets. Twenty‐four groundwater influencing factors (GIFs) were selected based on a multicollinearity test and the information gain calculation. The results of the groundwater potentiality mapping were validated using statistical measures and the receiver operating characteristic curve (ROC) method. Finally, a ranking of the 15 models was achieved with the prioritization rank method using the compound factor (CF) method. The ensembles of models are the most stable and suitable for groundwater potentiality mapping in mountainous aquifers compared to individual models based on success and prediction rate. The most efficient model using the area under the curve validation method is the RF‐LR‐DT‐ANN ensemble of models. Moreover, the results of the prioritization rank indicate that the best models are the RF‐DT and RF‐LR‐DT ensembles of models

Distribution of free amino acids, polyphenols and sugars of <i>Ziziphus jujuba</i> pulps harvested from plants grown in Tunisia

<div><p><i>Ziziphus jujuba</i> pulps are very much appreciated by the inhabitants and have been recently exported. This article reports on the chemical composition (amino acids, polyphenols and sugars) of the pulps of four <i>Z. jujuba</i> ecotypes (Choutrana, Mahdia, Mahres and Sfax). The major amino acids identified were proline, aspartic acid and glutamic acid. Among these, proline was the most abundant amino acid (17.4 mol). Considerable differences in total phenolic contents (15.85 mg/L) were found. Predominant phenols identified by using HPLC were rutin (1.09 mg/L) and chlorogenic acid (2.57 mg/100 g). Sugars isolated from <i>Ziziphus</i> pulps were found at a rate of 43.52%. Using HPLC method, three sugars from the pulp extract were identified: glucose, galactose and sucrose. The Mahdia ecotype was the richest in these sugars with 0.45, 136.51 and 113.28 mg/L, respectively.</p></div