28 research outputs found
Fractionation of Phosphorus in Surface Sediments Downstream of a Water Dam in Eastern Algeria
No full textAbstractThe mobility of phosphorus was examined in sediments sampled downstream Béni Haroun dam located in the northeast of Algeria. Sediment samples were collected in winter and spring 2010. They were characterized by the measurements of pH, electric conductivity, total phosphorus, organic carbon and heavy metals. In addition the infrared analysis was carried out. An analytical procedure involving sequential chemical extractions was used for the partitioning of phosphorus in several fractions. In the first scheme, five sedimentary phosphorus (P) reservoirs were separately quantified: loosely sorbed P, calcium bound P, metal oxides bound P, organic P and refractory P. In the second scheme, the distribution of inorganic phosphorus was estimated after removal of organic matter. The inorganic phosphorus mainly consisted of apatite fraction. The rank order of the different P extracts was the same for the two seasons. The contribution of each fraction was found to follow the order: apatite fraction metals oxides fraction, organic fraction, residual fraction, exchangeable fraction
Phosphate Removal from Aqueous Solution by Hydrous Iron Oxide Freshly Prepared Effects of pH, Iron Concentration and Competitive Ions
No full textAbstractIn the present work, the phosphate removal by hydrous iron oxide freshly prepared is studied. Experiments were conducted to study the effects of pH, iron concentration and the presence of sulphate, chromate, oxalate and certain metallic ions. Infrared spectroscopic analyses were performed to characterize the mechanism of phosphate interaction with the hydrous oxide in the absence and in the presence of the competitive ions. The results of macroscopic analyses show that the phosphate uptake is related to pH. The effect of iron concentration, suggests a certain saturation of adsorption sites. The effect of oxalate ions is more significant than those of chromate and sulphate ions. The presence of zinc and copper decreases the phosphate removal at pH > 7. In the absence of the other ions, the IR spectra of the solid samples show a broad band in the surrounding of 1030cm-1, characterizing the tetrahedral symmetry of phosphate. Among the studied anions, only chromate has an effect on the mechanism of phosphate ion retention by hydrous iron oxide freshly prepared
Characterization of Chromium (VI) Interaction with Rivers Sediments-In Relation to the Composition
No full textThe aim of the present work is to evaluate the mobility of chromium (VI) in aquatic systems by studying its interaction with different rivers sediments. The studied sediments were collected from the river Essouk which flows through a mining area in Skikda, and from the river Hemimime which flows through an industrial area in Constantine. The Cr(VI) fixation experiments on the studied sediments were carried out in batch. The results obtained show that the fixation of Cr(VI) is mainly related to the composition of the sediments. Sediments with a predominance of schwertmannite fix Cr(VI) better. The predominance of jarosite or calcite in sediments, implies a low Cr(VI) retention capacity. In the three cases, the kinetics of Cr(VI) fixation follows the pseudo-second order kinetic model. The adsorption isotherm is best described by the Freundlich model in the case of the jarosite predominance and by the Langmuir model in the case of the schwertmannite or the calcite predominance
Characterization of Phosphate Adsorption on Sediments
No full textAbstractPhosphate sorption by sediments sampled downstream of the Béni Haroun water dam was studied. Experiments were conducted to assess the effects of time, phosphate concentration, sediment dose, pH and temperature. Infrared spectroscopic analyses and sequential extractions were performed to characterize the mechanism of phosphate interaction with the sediments. The results of the macroscopic tests indicated that the fixing of phosphate ions is accomplished in two stages: the first rapid and the second slow. The kinetic data corresponded very well to a pseudo second-order equation. The equilibrium data was described by a Freundlich isotherm. The adsorption capacity increased with increasing temperature. It was highest in the pH range 7-8. In the IR spectrum, the adsorbed phosphate was characterized by a peak at approximately 1145cm-1 indicating relatively strong bonding between the adsorbed phosphate and the sorptive sites on the surface. In the sediments, phosphorus is mainly bound to calcium
Copper coprecipitation with hydrous iron oxide in aqueous solutions: spectroscopic, thermal and macroscopic analyses
No full textCharacterization of Dyes Adsorption on Carbonized Sewage Sludge
No full textABSTRACT In the present work, activated carbon was prepared and characterized in laboratory. Batch experiments were performed to test its adsorption affinity for Eriochrome Black T and Rhodamine b dyes. Kinetics and isotherms adsorption were evaluated and several models were used to describe the experimental data. The obtained results show that the prepared activated carbon is basic and is more efficient to remove the Eriochrome Black T. The calculated rate adsorption constants are about 0.0327 mg -1 .g.mn -1 for Eriochrome Black T removal and 0.0036 for Rhodamine b removal. For low concentrations, the adsorption isotherms are better described by Langmuir equation
Copper coprecipitation with hydrous iron oxide in aqueous solutions: spectroscopic, thermal and macroscopic analyses
No full textInternational audienc
Characterization of Cr(III) interaction with kaolinite – Effect of the presence of Cr(VI)
No full textInternational audienceIn the present study, experiments were performed to characterize the effectiveness of kaolinite in Cr(III) removal from water in the absence and in the presence of Cr(VI). The results of batch experiments, show that the efficiency of Cr(III) removal by kaolinite increases with the increase of pH and temperature in both cases. The effect of the presence of Cr(VI) on the adsorption of Cr(III) by kaolinite depends on the solution pH and on the concentrations of the two ions. Whatever the system, the removal kinetic of Cr(III) is well described by the pseudo-second order model. Spectroscopic analyses reveal that Cr(III) interaction with kaolinite is mainly electrostatic
Chemical Kinetic Modeling of Methane Combustion
No full textAbstractIn this work, we have developed a chemical kinetic modeling of methane combustion using a detailed kinetic mechanism including 213 elementary reactions and 48 species from literature. The mathematical model consists of a system of coupled ordinary differential equations resulting from kinetic rate laws. The solution is performed with a computer code in FORTRAN language based on the numerical fourth order Runge-Kutta method. The results show that the kinetic model used predicts efficiently the consumption of methane and oxygen as well as the production of water and carbon dioxide. However, the predicted nitrogen oxide formation (atmospheric pollutant) was less than the observed value
