الفهرس 
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Abstract
The use of micro algae Chlorella vulgaris and Scenedesmusquadricauda either free or immobilized in alginate or in spongy, composite to remove uranium from aqueous solution was examined under the effect of batch experiments. The experiments comprise different pH, concentrations of uranium, shaking and contact time. The maximum removal efficiency 82% for C. vulgaris and 84.8 % for S. quadricauda was indicated when the alga coated with alginate at pH 4.5 on horizontal shaker for 25 min at 300 rpm. In case of C. vulgaris the adsorption of uranium was evaluated with Langmuir isotherm R2= 0.99 with pseudo-second order where R2= 0.99, K2= 0.00086 and q2nd = 153.85 mg/g. In case of S. quadricauda the adsorption of uranium was evaluated with Langmuir isotherm R2= 0.99 with pseudo-second order where R2= 0.99, K2= 0.00268 and q2nd = 158.73 mg/g. The lowest value of K2 indicates that the great affinity of alga to adsorb uranium. An experiment was conducted to evaluate the toxicity of uranium to the microgreen algae.
Results indicated that the growth of alga was mostly decreased as compared with its corresponding control. The least reduction in the growth and growth parameters was found at 125 ppm. This means that uranium toxicity delayed the growth of two algae. The biosynthesis of pigments results manifested that uranium promote carotenoids rather than chl. a and b. For reducing the toxicity of uranium the alga was trapped in alginate form FT-IR Infrared spectra confirmed that the alga donates different functional groups and the layer in algal biomass is heterogeneity due to the variable characteristics peaks of amino, carboxylic, hydroxyl, and carbonyl groups. For this reason,two microgreen algae in alginate form is more efficient to adsorb and uptake uranium ions from aqueous solution.