Polypropylene membranes with high adsorption capacity and anti-adhesion properties achieved by hydrophobic interactions and hydrogen bonded self-assembly for uranium extraction from seawater

Herein, we have developed a mild and convenient strategy to enable polypropylene (PP) fibrous membranes with abundant adsorption sites for the selective extraction of uranium from seawater. Lysozyme was chosen as the pre-coatings because of its strong hydrophobic interactions with PP membranes. Then, lysozyme and phytic acid were set as hydrogen bonding self-assembling components since both of them are proved with a great binding affinity towards uranium. The contents and thickness of the lysozyme-phytic acid coatings could be linearly tuned due to the excellent controllability of self-assembly. The obtained PP membrane could achieve adsorption capacity as high as 90.07 mg-U/g-membrane (2143.83 mg-U/g-coating). In addition, the lysozyme would endow the PP membranes with outstanding anti-fouling, anti-bacteria, and anti-adhesion properties. The modified membranes could maintain more than 85% of adsorption capacity even with the interferences of bacteria and model pollutants. We also applied the membranes for dynamic adsorption by taking advantage of membrane filtrations. The adsorption capacity during the dynamic process increases with the flow rates and the layer numbers because more uranyl ions could contact with the adsorption sites. The modified PP membranes could obtain 1.15 mg/g of uranium after 15 days when the concentration of uranium is set as the same as the uranium concentration (3.3 μg/L) in natural seawater.