Effective and rapid adsorption of uranium via synergy of complexation and cation-π interaction

A novel indole-based aerogel (HTPRA) containing carboxyl groups was prepared for separation of uranium from aqueous solution. The adsorption was rapid, strongly dependent on pH, attaining a plateau at pH 4–7.5 and independent of ionic strength. The maximum adsorption capacity of HTPRA for uranium was evaluated to be 899.9 mg g−1. HTPRA exhibited satisfactory performance in actual water samples. Furthermore, the resulting HTPRA could be recovered at least five times without marked deterioration in uptake capacity. The synergistic effect of complexation and cation-π interaction between HTPRA and uranium was responsible for the unexpected adsorption capacity of uranium.