An investigation of the important parameters used for application of chemical reaction model at environmental soils in Egypt

Aquatic sediments are principally derived from weathering process. The Industrial wastes and mining activities are the potential sources of pollution. Uranium is a common element in the earth, it has moved and will be moved by naturally occurring geochemical process. Phosphates are usually from naturally and/or synthetic wastes. The objective of our research was to test of the environmental soils and/or sediments as an adsorbent media for the removal of uranium and phosphate compounds from environmental sediment samples. The coastal line sites such as Sharm El-Sheikh, Taba, Dahab and Hardgea attract over one millions tourists every year. Contamination by phosphates and uranium represented a great hazardous effect on the tourism industries. Studying of the pollution by the phosphate compounds especially with uranium is very important. The experimental procedures in this study were carried out using the above mentioned marine sediments and other fresh water sediments from other parts along the River Nile in Egypt. mineralogical investigations were carried out with X-ray diffraction technique. The sediment samples showed that it contained of the major kaolonite mixed with feldspar and quartz minerals. Chemical analyses of the sediments showed that the environmental sediments contain, 60 to 85% SiO2, 9 to 25% Al2O3 and 2 to 5% Fe2O3. carbonates were found 9 - 13% and the organics % are < 5%. Concentrations of the PO43- at the environmental sediments in aqueous distilled water was found 0.1 to 1.3 x 10-3 mg/kg , PO4-3 ions in the aqueous phase was found > 1.5 and 2 mg/kg at Port-Said and Rashid samples. Concentrations of the soluble UO2 was found less than 0.5 mg/kg at all the investigated samples. The pH of the soils in distilled water was found from 7.8 to 8.1, the pH of the Rashid sample was found 6.2. In order to obtain the limitation of the solubility of phosphate compounds. Different concentrations of PO4 were equilibrated with the fixed weights of the solid samples volume of the aqueous phosphate solutions ranged from 0.2 to 2 ppm were added to the dried sediment samples. Concentrations of PO43- remained at the aqueous phase were determined by the stannous chloride photometric method. The solid surfaces of environmental sediment and soils are amphoteric has a certain surface charge depends on the solution hydrogen ion concentrations. At a certain pH value, the solid surface has a net zero charge, in which the solid surface has no charge. The point of zero charge of the sediment samples were determined by the salt effect. The PZC was found 7 to 8 for all the samples. An example is shown of the determination of the PZC of sample (Dahab). The constant capacity model was used for the determination of the specific PO43- in equilibrium with solid phase. When a certain volume of distilled water were added to the environmental sediment samples, the slightly adsorbed phosphate and uranium ions were released, and sometimes phosphate only without uranium were released. Concentrations of the phosphates and uranium released depending on the pH of the solid in water. The species and the equilibrium constants of PO43- in water - sediment system at a certain pH value. The results showed, by the ion activity products (IAP). The saturation index (SI) was calculated and equal log (IAP/Keq.), so, when SI = 0, the phosphate compound was in equilibrium with the solid phase, when, SI has a negative value, the phosphate compound will dissolve and when SI has a positive value, the phosphate compound will precipitate. Keq was used from the reactions of the Equations shown. The results showed that, phosphate ions was in equilibrium with the solid phase at phosphate concentration 1.3 x 10-3 mg/kg, PO43- ions was soluble at the concentrations 0.01 to 0.1 x 10-3 mg/kg, PO43- ions was precipitated at the concentrations > 1.5 x 10-3 mg/kg and uranium was soluble at the concentrations < 0.5 x 10-3 mg/kg. Phosphate compounds at most of the sediments of the River Nile, Agamy, Port-Said and Rashid samples are over saturated that is mean that these sites are more polluted and the uranyl phosphate compound has a great hazardous effect on the living organisms