Removal of Th4+ ions from aqueous solutions by graphene oxide

The removal of Th4+ ions from aqueous solutions was investigated using single-layer graphene oxide (GO) as a sorbent which was prepared by the modified Hummers' method through batch adsorption experiments at room temperature. Structural characterizations of the sorbent were also investigated. The influences of the pH value of solution, contact time, sorbent dose, ionic strength, the initial metal ion concentration and temperature on the adsorption of Th4+ were also investigated. These results indicated that the adsorption of Th4+ was dependent on the pH and independent on the ionic strength. The sorbent provided significant Th4+ removal (> 98.7 %) at pH 3.0 and the adsorption equilibrium was achieved after only 10 min. The Langmuir adsorption isotherm fit the absorption profile very closely, and indicated that a maximum adsorption capacity of 1.77 mmol g(-1) of GO (411 mg g(-1)) after 2 h. The thermodynamic parameters showed that this adsorption process was endothermic and spontaneous. Moreover, the desorption level of Th4+ from GO, by using 0.1 mol L-1 H2SO4 as a stripping agent, was 84.2 +/- A 1.2 %, and that of 0.5 mol L-1 HNO3 as a stripping agent, was 79.8 +/- A 3.0 %.