The mathematical model for the potentiostatic work of CP-based electrochemical sensors and biosensors, used for the detection of two strong organic acids with the common “acid” functional group (using the example of –SO3H group), was developed and analyzed by the using of linear stability theory and bifurcation analysis. The steady-state stability conditions, corresponding to the better response, were developed. The presence of oscillatory and monotonic instabilities was also confirmed.

The possibility of diquat electrochemical detection, realized by conducting polymer electrode, doped by vanadium dioxide, was analyzed by theoretical point of view. It was shown, that the conducting polymer composite with VO2 may serve as an excellent electrode modifier for Diquat electrochemical detection. The steady-state may be maintained stable in the vast parameter region. The possibility for electrochemical instabilities in this system has also been studied.

Solidification/Stabilization treatment of the exhausted oil-based drilling sludge using hydraulic binders, followed by a compaction at the paste phase, was used to reduce the mobility of the pollutants while improving the physical properties of the sludge. The treatment involved mixing the exhausted sludge with required quantities of hydraulic binders such as: Portland artificial cement, air quicklime and water, corresponding to the formulations tested. The obtained smooth paste was subjected to the compaction tests using a triaxial press for the production of standard specimens, in which, leaching tests, chemical analysis and compressive strength measurements were carried out after 30, 60 and 90 days curing. Results revealed that the compaction at the paste phase resulted in optimizing the amount of hydraulic binders and water and improving the retention capacity of pollutants in a cementing matrix compared to previous works. Furthermore, it led to the improvement of the mechanical properties of the stabilized/solidified sludge.

The texture properties and adsorption affinity of Hematite Sand (HS) were studied by nitrogen at 77 K and methylene blue dye adsorption in aqueous phase, respectively. Characterization of raw HS and treated HS was performed. The experimental data were fitted to Langmuir as well as Freundlich adsorption isotherm equations using non-linear regression method. According to the BJH, 40 % of the total pore volume disappeared on treated HS surface after sieving process and acid treatment due to absence of microspores. Finally, the dye adsorption was influenced significantly by solution pH and the presence of inorganic salt (KCl)

In the present study, we carried out a bibliographic and analytically research on the various sources of pollution of wade Beht, by analysing the physicochemical parameters (pH, temperature, conductivity and turbidity) and biological parameters (DCO and DBO5) in water samples taken at five sampling points, to determine the degree of pollution. The results of the analysis of the physicochemical and biological parameters envisaged in this work were recorded in the following order: 7.6 ≤ pH ≤ 8.6, 20 °C for temperature, the conductivity was between 2900 and 3000 μS/cm for the first four sampling points while that measured for the discharge of the SURAC was obtained in the order of 3100 μS/cm. The control of the general parameters of the pollution at the point of evacuation point of the releases of the industry SURAC displayed the results in the order of 300 mg O2/l for DCO and 120 mg O2/l for DBO5. From the results obtained at the end of this study, we found that the measured values are higher than those indicated in the standards of the surface water quality grid, which means that the quality of the bottom waters wade Beht varied from bad to very bad.

The problem of agricultural pesticide utilization in the Arab countries is not only an issue of uncontrolled use, but it is also a problem pertaining to the handling, misuse and disposal of unwanted pesticides. Electrochemical measurements were performed using a computer controlled by Potentiostat/Galvanostat model PGZ 100 associated to ‘‘Volta-Master 4’’ software. The chemical oxygen demand  (COD) is measured according to the standard methods for examination of water and wastewater. The COD values were determined by the open reflux, with dichromate titration method. All measurements were repeated in triplicate and all results were observed to be repeatable within a 5 % margin of experimental error. Kinetic studies were carried out to determine the COD reduction efficiency for electrooxidation pesticides at different supporting electrolytes. For this purpose, the removal rate of COD was assumed to obey a first-order kinetic as follows. The influence of the current density on the COD removal during the electrochemical oxidation of pesticide Azoxystrobin was 40 mg L-1 at the BDD anode.

In order to find a correlation between the structures of the dihydropyrimidones derivatives with the in vitro inhibitory activity of β-glucuronidase, a Quantitative Structure-Activity Relationship (QSAR) study is applied. This will be achieved using Principal Component Analysis (PCA), Multiple Linear Regression (MLR), Multiple Nonlinear Regression (MNLR) and Artificial Neural Network (ANN). Finally, the cross-validation method (CV) with the leave-one-out (LOO) procedure is used to test the performance of the neural network, the validity of the selection of the selected descriptors and the proposed model.

With over-mining of the natural rock-P, food production will plummet sooner than we envisage since they are essential in agro-business but are non-renewable. Consequently, phosphate fertilizers are going to be limited in future. Struvite is a crystalline mineral substance containing equimolar amount (1:1:1) of magnesium, ammonium and phosphate ions (MgNH4PO4·6H2O), a good source of phosphorus and a slow-release fertilizer. In this study, Epsom salt was used as a source of magnesium to recover phosphate by crystallization from cow urine. Characterization of the precipitates was done through Scanning Electron Microscopy and Energy Dispersive X-ray, Fourier Transform Infrared, X-ray Diffraction and Thermogravimetric and Differential Thermal analyses to determine its suitability for use as a slow-release fertilizer for agricultural purposes. The production of struvite as crystal fertilizer will be an effective alternative source of phosphorus when the natural phosphate is exhausted. This phenomenon being eco-recycling of phosphorus, nitrogen and magnesium yields eco-friendly fertilizer needed for food security and can help mitigate the problem of eutrophication.

Natural vegetation plays a vital role in the balance of the earth's environment, thanks to its multiple functions as purifier, producer and protector. And the monitoring of vegetation in Sahel regions with Remote Sensing data has become increasingly important over the past decade because it is linked to variation in agricultural production and climate change with implications for wildlife management and tourism. Recent advances in Remote Sensing applied make it possible to better characterize vegetation, but also monitoring its spatio-temporal dynamics. This study aims to extract vegetation cover in the National Park of Niokolo-Koba and analyze its changes over a period of 45 years. In doing so, four Landsat images recorded on 1972 (MSS), 1986 (TM), 2000 (ETM+), 2005 (ETM+), 2011 (TM) and 2014 (OLI_TRIS) were used to minimize change detection error introduced by seasonal differences. Images were geometrically and radiometrically corrected. Normalized difference vegetation index (NDVI) is chosen to extract and classify vegetation. Post-classification comparison was applied to Landsat multi-temporal imagery to determine ‘from–to’ change information derived from the classifications maps. The overall accuracy obtained for single classifications is 81.72% (1972), 84.32% (1986), 89.49% (2002) and 93.50% (2016). And for change results, the overall accuracy calculated through the no-change / change error matrix is considered good, with 74.90%, 78.90 and 80.72% for the 1972-1986, 1986-2002 and 2002-2016 images pairs, respectively. These results made it possible to identify the spatial and temporal dynamic of the vegetation within the Park between 1972 and 2016. A spatial regression of the gallery forest and woodland savannah between 1972-1986 and 1986-2002 was observed, to the detriment of the Shrubland and grassy savanna. Nevertheless, between 2002 and 2016 the situation is reversed, notably with an upward trend of the forests gallery and shrub savannah classes. There is also an alternating phase of progression and regression of wetlands. A high correlation (r² > 0.60) is established between each class of vegetation and rainfall variability. This study is part of an integrated management approach to protected areas in Senegal. It is a first approach to monitoring the vegetation of the Niokolo-Koba National Park by using remote sensed data and helps to understand the trends observed in the dynamics of forest resources.

In the present work, we have conducted a study which is to study the mechanical and hydrodynamic performance (permeability and selectivity) of two asymmetric ultrafiltration membranes, the base matrix is polysulfone PSU UDEL P1700 [1-3]. The first type of these membranes is composed only of polysulfone and the second type is made from polysulfone and polystyrene expanded (PSe) [2]. Both membranes were used in the bleaching of waste water loaded with vat dyes (indigo and sulfur black) by using the technical ultrafiltration (UF), while optimizing the hydrodynamic and mechanical conditions of harvested membranes [2, 4]. The results of this study have been shown that the selectivity and the permeability of the PSU/PSe membrane are more efficient with respect to those of the membrane completely comprised of PSU, on the one hand, and the measured values of the fading rate water loaded with the black sulfur dyes and indigo were recorded respectively at percentages 60.78% and 80.36% appropriate the membrane consisting of PSU only and at percentages 64.04% and 87.24% for the membrane composed of PSU/PSe, the other.The results of this study, we showed that adding PSe in very small quantities in the mixture of polysulfone only has increased mechanical and separative properties (permeability and selectivity) of the resulting membrane..