Uranium and its decay products can be found in the environment through a wide array of anthropogenic activities such as mining, nuclear and power generation industries and the production of phosphate fertilizers .(Sprynskyy et al. 2011) They pose a severe, long term ecological and public health threat (Khani 2011, Landa 2003) and therefore there is a considerable effort in the removal of these pollutants before their final discharge in the environment, as well as their recovery as an energy resource (Pang et al. 2011). For this purpose, common physico-chemical techniques (e.g. electrochemical treatment, ion-exchange, reverse osmosis, precipitation etc.) have been practiced for decades. But these techniques exhibit serious drawbacks such as
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The vials were rotated end-over end on a rotary shaker to keep suspensions homogeneous throughout the sorption period. Past equilibration time of 24 hours, the suspensions were centrifuged to separate the fluid phase from the solid substrate and a portion of the supernatant was analyzed for remaining uranium concentration. The effect of solid:liquid ratio was studied for biomass concentrations ranging from 1 to 12.5 mg mL-1, initial U(VI) concentration 800 mg L-1, I=0.1M NaClO4 at 25 oC, equilibrated for 24h. In the kinetic studies, GS were allowed to equilibrate with the solution for different time periods with 10 mL of solution containing 800 mg U(VI) L-1, at 15, 25 and 33 oC. In equilibrium studies, the initial U(VI) concentration was in the range between 25 – 800 mg L-1 at 15, 25 and 33 oC. In all experiments, either kinetic or equilibrium, the ionic strength of the solution was kept constant at 0.1 M with NaClO4. The effect of ionic strength was studied by suspending 0.010 g GS in 10 mL of 250 mg U(VI) L-1 with ionic strength varying from 0.001-0.5 M NaClO4 at 25 oC for 24 h.
2.4 Effect of inorganic and organic ligands
In order to explore the effect of inorganic and organic ligands on uranium uptake, 0.010 g of GS were equilibrated for 24 h with 10 mL of solution containing 250 mg U(VI) L-1, pH 3 at 25 oC at different ligands concentrations. More specifically, concentrations ranged 0.001-0.5 M for NO3- and Cl-, 0.001-0.02 for HCOO- and CH3COO-, 0.01-0.1 M for C6H5O73- and 0.001-0.1 M for
The vials were rotated end-over end on a rotary shaker to keep suspensions homogeneous throughout the sorption period. Past equilibration time of 24 hours, the suspensions were centrifuged to separate the fluid phase from the solid substrate and a portion of the supernatant was analyzed for remaining uranium concentration. The effect of solid:liquid ratio was studied for biomass concentrations ranging from 1 to 12.5 mg mL-1, initial U(VI) concentration 800 mg L-1, I=0.1M NaClO4 at 25 oC, equilibrated for 24h. In the kinetic studies, GS were allowed to equilibrate with the solution for different time periods with 10 mL of solution containing 800 mg U(VI) L-1, at 15, 25 and 33 oC. In equilibrium studies, the initial U(VI) concentration was in the range between 25 – 800 mg L-1 at 15, 25 and 33 oC. In all experiments, either kinetic or equilibrium, the ionic strength of the solution was kept constant at 0.1 M with NaClO4. The effect of ionic strength was studied by suspending 0.010 g GS in 10 mL of 250 mg U(VI) L-1 with ionic strength varying from 0.001-0.5 M NaClO4 at 25 oC for 24 h.
2.4 Effect of inorganic and organic ligands
In order to explore the effect of inorganic and organic ligands on uranium uptake, 0.010 g of GS were equilibrated for 24 h with 10 mL of solution containing 250 mg U(VI) L-1, pH 3 at 25 oC at different ligands concentrations. More specifically, concentrations ranged 0.001-0.5 M for NO3- and Cl-, 0.001-0.02 for HCOO- and CH3COO-, 0.01-0.1 M for C6H5O73- and 0.001-0.1 M for