Preparation of amidoxime functionalized titanate nanosheets for efficient extraction of uranium from aqueous solution

An efficient adsorbent of amidoxime-decorated titanate nanosheets (TNSs-AO) were prepared and characterized by multiple analytical methods (XRD, TEM, FTIR and TGA). Batch experiments were performed systematically to investigate the influence of the operational parameters such as adsorbent dosage, initinal U(VI) concentration, solution pH, reaction time and temperature on the adsorption performance, as well as evaluate adsorption performance in simulated seawater. Experimental data showed that TNSS-AO presented more excellent U(VI) ions binding affinity than TNSs, and that the optimal pH regime of TNSs-AO was wider than that of TNSs. Langmuir model was more suitable for explaining equilibrium data, and the monolayer adsorption capacity of TNSs and TNSs-AO were 240.38 mg/g and 401.61 mg/g, respectively. The adsorption process followed the pseudo-second-order rate equation, indicating chemical adsorption was the mian mechanism in the adsorbate-adsorbent interactions. Thermodynamic studies indicated the adsorption process was spontaneous and endothermic. By means of FT-IR and XPS, it was concluded that surface complexation and ion exchange were the main adsorption mechanisms. Moreover, adsorption performance in simulated seawater system suggested the feasibility of TNSs-AO in the presence of multiple interfering ions. Therefore, the as-obtained TNSs-AO could be potentially used as a promising adsorbent for the preconcentration and separation of U(VI) from aqueous solutions.