Application Of Multivariate Statistical Methods To Surface Water And Groundwater Of The Soummam Basin, Algeria

Multivariate statistical methods, i.e., cluster analysis (CA), discriminant analysis (DA) and analysis of variance (ANOVA), were used to assess spatial variation in the water quality of the Soummam basin, Algeria. The application of hierarchical cluster analysis, based on all possible combinations of classification method, showed three main groups of samples. The group 1 samples are exclusively composed of surface water. Groups 2 and 3 samples are consisted of groundwater. Discriminant analysis (DA) was assigned about 98.6% of the cases grouped by CA. All groups are super-saturation with Ca-montmorillonite, dolomite, gibbsite, K-mica, kaolinite and quartz, and all these groups are under-saturation with albite, anhydrite, anorthite, CO2(g), gypsum, halite, melanterite and smithsonite. The ANOVA results indicate that the saturation indices of each of the mineral phases are significantly except chalcedony and quartz (p \u3e 0.05)

Assessment of Heavy Metals Contamination in Groundwater: A Case Study of the South of Setif Area, East Algeria

Heavy metals in groundwater were analyzed and their sources and impacts were identified using multivariate statistical tools and risk assessment. Three significant factors were extracted by factor analysis (FA), explaining 75.69% of total variance. These factors were in turn described by the clusters C3, C2 and C1, respectively, resulting from the cluster analysis (CA). Factor analysis and cluster analysis revealed significant anthropogenic contributions and water-rock interaction effects of the metals in groundwater. The mean values of heavy metal evaluation index (HEI) and degree of contamination (Cdeg) indices indicated that the groundwater samples were contaminated with high degree of pollution by cadmium (Cd) and lead (Pb). The hazard quotients (via ingestion) of Cd and Pb were found to be higher than the safe limits, posing threat to the consumers. However, no risk related to the dermal contact was associated with the measured metal levels

Monometal and competitive sorption of heavy metals in mine soils: Influence of mine soil characteristics

pas de DOI / http://www.researchgate.net/publication/236158313International audienceThe environmental and health effects of the contamination of soils by heavy metals depend on the ability of the soils to immobilize these contaminants. This study was conducted to assess the monometallic and competitive sorption of lead, copper, zinc and cadmiumin surface samples of four soils from eastern Algeria. Sorption isotherms were characterized using Freundlich and Langmuir equations. Retention selectivity sequences indicate that, inmost of the soils, Pb is the preferred retainedmetal, followed by Cu. The last metals in these sequences are Cd and Zn.All soils showed greater sorption capacity. On the basis of distribution coefficient values for the metal concentration of 100 mg. l-1 (Kd100) for each soil and trace element, the two most common adsorption sequences found were Pb>>Cu>Cd>Zn and Pb>>Cu>Zn>Cd. Competition significantly reduced metal Kd, especially that of Cd

Suitability and Assessment of Surface Water for Irrigation Purpose

Surface water is an important resource that can create tensions between different countries sharing the same water sources to know that the agriculture is considered as the last sector that exploits less water compared to the industry which uses very large water quantities. The future strategies of agricultural development in the most of these countries depend on the ability to maintain, improve and expand irrigated agriculture. In this light, this chapter is written in the way to show some steps of the evaluation of surface water for irrigation purpose. The results obtained from this research make it possible to evaluate the suitability of surface water for irrigation and to draw useful recommendations for dam managers and farmers

A DFT and experimental investigation of the electron affinity of the triscyclopentadienyl uranium complexes Cp3UX

International audienceRelativistic Density Functional Theory (DFT) based methods coupled with the Conductor-like Screening Model (COSMO) for a realistic solvation approach are used to investigate the electron affinity (EA) of a series of triscyclopentadienyl uranium complexes Cp3UX (X = Cl, BH4, SPh, SiPr and OiPr) related to the U(IV)/U(III) redox system. E1/2 half-wave potentials have been measured in solution (THF) under the same rigorous conditions for all the species under consideration. A good correlation (r2 = 0.99) is found between the computed EA values, either in the gas phase or in solution, and the experimental half-wave potentials; the study brings to light the importance of spin-orbit coupling effects which must be taken into account in order to achieve the observed agreement between theory and experiment. The influence of the electron donating character of the X ligand on the orbital involved in the reduction process, namely the lowest unoccupied molecular orbital (LUMO) of the neutral U(IV) complexes, and on the EAs is discussed

Magnetic exchange coupling in imido bimetallic uranium(V) complexes. A relativistic DFT study

International audienceMagnetic exchange coupling between uranium U(V) ions, in the case of the two para- and meta-imido diuranium complexes, respectively [(C5H5)3U]2(μ-1,4-N2C6H4) and [(C5H5)3U]2(μ-1,3-N2C6H4) exhibiting the 5f1-5f1 configuration, have been investigated using relativistic DFT calculations, combined with the broken symmetry (BS) approach. Using the B3LYP functional, the singlet BS state of the para complex has been found of lower energy than the high spin (HS) triplet one, in agreement with the observed antiferromagnetic character of the complex. On the contrary the BP86 functional fails to predict this magnetic property. The spin density distributions and MO analysis explain well the antiferromagnetic character of the para complex and clarify the failure of the BP86 functional. The effective participation of the 5f metal orbitals in bonding with the imido ligand plays a key role for electronic and magnetic communication between the two active U(V) 5f1 electrons. The same technique led us to explain the ferromagnetic character of the meta isomer in agreement with experiment. For both isomers the spin polarization mechanism explains well their observed magnetic behaviour

DFT Investigations of the Magnetic Properties of Actinide Complexes

International audienceOver the past 25 years, magnetic actinide complexes have been the object of considerable attention, not only at the experimental level, but also at the theoretical one. Such systems are of great interest, owing to the well-known larger spin-orbit coupling for actinide ions, and could exhibit slow relaxation of the magnetization, arising from a large anisotropy barrier, and magnetic hysteresis of purely molecular origin below a given blocking temperature. Furthermore, more diffuse 5f orbitals than lanthanide 4f ones (more covalency) could lead to stronger magnetic super-exchange. On the other hand, the extraordinary experimental challenges of actinide complexes chemistry, because of their rarity and toxicity, afford computational chemistry a particularly valuable role. However, for such a purpose, the use of a multiconfigurational post-Hartree-Fock approach is required, but such an approach is computationally demanding for polymetallic systems-notably for actinide ones-and usually simplified models are considered instead of the actual systems. Thus, Density Functional Theory (DFT) appears as an alternative tool to compute magnetic exchange coupling and to explore the electronic structure and magnetic properties of actinide-containing molecules, especially when the considered systems are very large. In this paper, relevant achievements regarding DFT investigations of the magnetic properties of actinide complexes are surveyed, with particular emphasis on some representative examples that illustrate the subject, including actinides in Single Molecular Magnets (SMMs) and systems featuring metal-metal super-exchange coupling interactions. Examples are drawn from studies that are either entirely computational or are combined experimental/computational investigations in which the latter play a significant role

A relativistic DFT study of cyclopentadienyl actinide complexes with no transition-metal analogues

International audienceThe geometry and electronic structure of several tris and tetrakis-cyclopentadienyl thorium and uranium complexes have been investigated using Density Functional theory (DFT) calculations in the framework of the relativistic zeroth-order regular approximation (ZORA) implemented in the ADF (Amsterdam density functional) program. In all cases, the important interaction between the metal 5f orbitals and the Cp3 moiety is brought to light. However, coordination with a fourth ligand like H− or Cl− leading to Cp3AnL species involves mainly the metal 6d orbitals, whereas in the case of L = Cp−, the 5f uranium orbitals act also efficiently. The actinide 5f orbitals are more efficient in uranium than in thorium for metal to ligand bonding. Cyclopentadienyl to uranium donation is enhanced when the metal ion charge increases. Finally, our calculations indicate that the Cp3UH structure could be thermodynamically stable, although it has not yet been synthesized

Removal of Pb2+ and Zn2+ from the aqueous solutions by activated carbon prepared from Dates stone

International audienceThe low-cost activated carbon prepared from Date stone, an agricultural solid waste by-product, were prepared by chemical activation with sulphuric acid for the removal of lead and zinc from aqueous solutions has been studied as a function of pH, contact time, metal concentrations and adsorbent concentrations. Adsorption equilibrium was reached after an equilibration time of 60 min and adsorption kinetics data were tested using Lagergren pseudo-first-order and pseudo-second order, the studies showed the adsorption process followed pseudo-second-order rate model. The maximum removal of Pb2+ and Zn2+ is observed at pH 6.0 (94.4%) and 7.0 (93.2%) respectively at initial concentration 20 mg/L. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. The adsorption capacity q max) calculated from the Langmuir isotherm was 19.64 mg Pb2+/g and 10.41 mg Zn2+/g at an initial pH of 6.0 at 20 ± 2°C

The Numerical Results of the Magnetic Behavior of the Thin-layers SFCL

The performance of superconducting current limiters associating the short-circuit phenomenon depends on the structure of the superconducting material envisaged and on the way of inserting it into the electrical network.  In this paper, we present some numerical results of the magnetic behavior of superconducting fault current limiters (SFCLs). To describe the relationship between the electric field and the current density inside the thin-film superconductor