Because the concentration of uranyl ions in seawater is very low, adsorption agents used for this process must be particularly efficient. By carefully controlling the surface and pore structures, a team from Oak Ridge National Laboratory and the University of Tennessee has now been able to significantly increase both the rate and capacity of adsorption of a new polymer adsorbent.
Their success stems from a special polymerization technique. Sheng Dai’s team begins by producing a porous polymer framework based on the monomer vinylbenzyl chloride (VBC) with divinylbenzene (DVB) as a cross-linking agent. It is possible to vary the surface properties and pore volume of the product by changing the ratio of VBC to DVB. The interiors of the resulting frameworks contain many accessible chloride species that then serve as starting points for the next polymerization step, which is known as atom-transfer radical polymerization (ATRP). This reaction allows the researchers to grow polyacrylonitrile chains within the framework. The advantage of ATRP is that the length of the chains is highly controllable and uniform. In the final step, the polyacrylonitrile is converted to polyamidoxime because amidoxime groups bind well to uranyl ions.
Read more at: Phys.org