Polyacrylate/phytic acid hydrogel derived phosphate-rich macroporous carbon foam for high-efficiency uranium adsorption

Abstract

The development and application of new high-efficiency adsorbent materials for efficient removal of uranium (VI) from nuclear wastewater is of great concern for environment protection. In this study, a novel phosphate-rich macroporous carbon foam was designed and synthesized for efficient uranium (VI) adsorption. Bath adsorption was used to evaluate the uranium (VI) adsorption performance of this carbon foam, and the influences of adsorbent dosage, solution pH and ionic strength on adsorption efficiency were studied. The results demonstrated that the carbon foam was effective adsorbent for uranium (VI) and the adsorption efficiency reached 99 % at 30 °C, pH 7.0 and contact time 2.0 h with an adsorbent dosage of 0.25 g L−1 in 100 mg L−1 uranium (VI) solution. The adsorption process follows better with pseudo-second-order model with a coefficient of correlation of 0.9999 and was more consistent with the Langmuir model with the maximum adsorption capacity as high as 1250 mg g−1. The distribution coefficient of carbon foam for uranium (VI) reached 15 L g−1 which is higher than that for other ions (0.1–4.4 L g−1), demonstrating a good adsorption selectivity. Moreover, this material can be recycled for at least 5 times and can be used in fixed-bed adsorption column for dynamic adsorption of uranium from uranium-containing solutions (5 or 50 mg L−1) with adsorption efficiencies up to 99 %. This study's results showed the high efficiency of phosphate-rich macroporous carbon foam in uranium (VI) adsorption and highlighted its great potential in efficient removal of uranium (VI) from nuclear wastewater.