Modified adsorbent with conductive polymer grabs uranium from seawater quickly

Earth’s oceans contain more than 4 billion metric tons of dissolved uranium. That’s roughly 1,000 times as much as all known terrestrial sources combined, and enough to keep the world’s nuclear power plants running for centuries. But because the oceans are enormous and uranium’s concentration in seawater is so low—roughly 3 ppb—extracting the metal is a tough job. A new adsorbent featuring conductive polymer chains may make that task easier (Chem 2020, DOI: 10.1016/j.chempr.2020.04.012). Ye Yuan and Guangshan Zhu of Northeast Normal University and coworkers sought to improve the uranium uptake properties of a promising porous aromatic material, MISS-PAF-1, that they had used in earlier studies to extract uranium via an electrochemical method. That material traps uranyl ions at adsorption sites containing salicylaldoxime groups. To boost the performance, the researchers threaded MISS-PAF-1’s channels with poly(phenylacetylene), reasoning that the conductive chains would provide a pathway for ion transport and concentrate uranyl ions near adsorption sites. Tests on natural seawater show that modified MISS-PAF-1 extracts uranium more than three times as fast as the unmodified adsorbent and several reference adsorbents, trapping 13 mg of uranium per gram of adsorbent in 56 days.