Aluminum-based metal-organic frameworks (CAU-1) highly efficient UO22+ and TcO4− ions immobilization from aqueous solution

Abstract

In this research, an Al-based metal-organic framework (MOFs), CAU-1 was prepared through complexation between 2-aminoterephthalic acid and Al (III) by solvothermal approach, and simple operation and cost-effective synthetic route. The objective was to immobilize the typical positive/negative radionuclide ions (UO22+/TcO4−) in aqueous solution. The synthesized CAU-1 was characterized by XRD, FT-IR, TGA, FESEM, TEM-SAED, pHpzc, XPS and N2 physisorption analysis. The structure of CAU-1 possessed excellent thermostability, rich functional groups (‒NH2 and ‒OH groups), as well as large surface area (1636.3 m2/g) and the micropore volume (0.51 m3/g). Furthermore, batch experiments demonstrated that CAU-1 with superior adsorption capacity was 648.37 (UO22+) mg/g and 692.33 (ReO4−) mg/g calculating from Langmuir isotherm model, respectively. Thermodynamic investigation showed the adsorption process was endothermic and spontaneous. In addition, the adsorption mechanism of ReO4− ion onto CAU-1 could be electrostatic attraction and chelation effect, while for UO22+ ion, was mainly chelation effect induced by nitrogen-containing and oxygen-containing functional groups. Hence, the inexpensive and high-capacity CAU-1 could be considered as a practical material for sequestrations of radioactive pollutants from water environment.