3.3 Uranium recovery in seawater
To analyze the uranium adsorption capacity of AO-Fc in real seawater, adsorbent (7 mg) was added in a homemade adsorbent holder (syringe, Figure S1) and exposed to 20 L seawater and the complete home-made uranium adsorption set-up was shown in (Figure S1). The amount of uranium adsorbed from seawater was analyzed by knowing uranium concentration at different time intervals using (ICP-MS). For industrial applications, the adsorbent can be directly used to lower surface seawater for uranium extraction. The uranium adsorption kinetic results revealed that AO-Fc showed 6.60 mg/g adsorption capacity within one week, which was 75% of the total uranium adsorption. The maximum adsorption capacity reached 8.57 mg/g with 100 % adsorption efficiency after 11 days of the adsorption experiment (Figure 9ab). In comparison, AO-Fc showed efficient uranium adsorption from seawater (Table 5). Uranium adsorption capacity reflects the direct measurement of the amount of uranium adsorbed by an adsorbent and the distribution coefficient (Kd), determines the adsorbent affinity towards adsorbate. These results indicated that the adsorbent retaining high uranium adsorption capacity in presence of other coexisting ions might have a correspondingly higher Kd value than other coexisting ions in Figure 9c. Based on that, the evaluation of Kd (L/g)is an important parameter for choosing the most suitable adsorbent for further analysis.
Figure 9 Kinetics of uranium extraction (a,b) and distribution coefficient (Kd) of various ions in natural seawater (b)
Table 5 Comparison of various adsorbents for uranium extraction in seawater