சுற்றுச்சூழல் பகுப்பாய்வு வேதியியல் இதழ்

This work is a contribution to the study of the quality of drinking water in Niger Republic. It concerns the physicochemical characterization of Tibiri drinking water. Thus, pH, conductivity, temperature and, some anions (nitrates, chlorides, fluorides, and bicarbonates) concentration are evaluated. The results obtained showed that this water are acidic and not agree WHO standards of drinking water; their conductivity indicate that their degree of mineralization is low and obey also to the WHO standards; the temperature measured as well as anions concentrations determined are in agreement with WHO standards. Therefore, Tibiri drinking water quality is quite good in terms of temperature, conductivity, and ions analyzed.

An amine terminated G 5.0 Polyamidoamine dendrimer was functionalized with Succinic anhydride and immobilized on chromatography grade silica gel to produce a functionalized dendrimer-silica composite (G-5- PAMAM-SGA). The composite was characterized using Fourier Transform-Infra Red spectroscopy, Brunauer Emmett and Teller surface area analysis, Thermogravimetric Analysis, Zeta Potential, and Scanning Electron Microscopy. Adsorption properties of the synthesized composite were studied by batch adsorption method using Cd (II) as adsorbate. The sorption process was analyzed using 6 different isotherm models (Langmuir, Freundlich, Harkins-Jura, Sips, Jossens and Baudu).

The experimental data were best fitted into Jossens isotherm model (R²=0.981) the order of fitting for the models is Jossens>Baudu>Harkins-Jura>Sips>Freundlich>Langmuir. The maximum adsorption capacity of G-5- PAMAM-SGA for Cd (II) was 123.4 mg g^-1 and the system was influenced by temperature, initial concentration and pH. Analysis of sorption kinetics reveals that the data fitted better to the pseudo-second-order model than any other kinetic model, signifying that the sorption process involved is chemisorption. Sticking probability (S^*=0.9999), suggesting a mixture of chemisorption and physisorption (coordination adsorption). Gibbs free energy of adsorption at 293,303 and 313 K were all negative thus sorption was spontaneous and favorable.

JSC “NIUIF”, the oldest (founded in 1919) and the only one in Russia scientific research institute for phosphorus containing fertilizers, developed an innovative flexible technology of production of slow release NPKS / PKSfertilizers with a controlled dissolution rate and controlled nutrient supply into the soil solution. These fertilizers are environmentally safe, nonradioactive; practically do not contain compounds of harmful heavy metals (arsenic, cadmium, lead, mercury, chromium, etc.). Besides the main nutrients (nitrogen, phosphorus, potassium) they also contain sulfur and calcium in a plant available form. The dissolution rate is regulated by changing the ratio between the water soluble and plant-available forms of phosphorus, as well as by addition of ammonium salts. The technology is waste free, moreover, it allows to process wastes and by-products of other production units: phosphogypsum, conversion chalk, cake from sodium tripolyphosphate production, sludge sand, etc. These fertilizers were successfully tested by the International Institute of Plant Nutrition and in the Russian Agricultural Academy named after K.A.Timiryazev to prove its high agronomic efficiency. The technology is protected by three patents of the Russian Federation. Based on the design documentation developed by JSC “NIUIF”, NPKS / PKSfertilizer plant was built and successfully set into operation at “Metakhim” plant (Volkhov city, Leningrad Region).