Preparation of functionalized nanoporous carbons for uranium loading

Ordered nanoporous carbons (CMK-3) with submicron-scale particle size were functionalized with carboxymethylated polyethyleneimine (CMPEI) as a new uranium loading material to increase uranium adsorption capacity, and characterized by Fourier transform-infrared spectroscopy (FT-IR) and powder X-ray diffraction (XRD). The adsorption isotherm of uranyl ions on the functionalized carbons was examined and evaluated using the Langmuir adsorption isotherm model. It was found that the adsorption of uranyl ions on the functionalized carbons follows the Langmuir isotherm model. The maximum uranium adsorption capacity of the adsorbent by the Langmuir model was calculated to be 151.5 mg U/g adsorbent. The loading stability of uranium on the adsorbent was examined at pH 4. It was observed that about 30% of uranium was released from CMPEI/CMK-3 within a day, however, uranium contents almost linearly decreased with a low desorption rate from 1 to 20 days.