Design And Study Of Robust And Anti-fouling Adsorbents For Uranium Extraction From Seawater

Uranium extraction from seawater has received extensive attention for solving the shortage of nuclear energy supply and make it sustainable.It is reported that there are about 4.5 billion tons of uranium in the ocean.However,the low concentration of uranium in the ocean（about 3.3 ppb）,the large number of competitive ions and the presence of many marine microorganisms make effective uranium extraction chal enging.Therefore,it is of practical significance to develop adsorbents with good adsorption performances and anti-fouling abilities.In this paper,two kinds of adsorbents with anti-fouling properties were designed to solve the problem of bacterial adhesion caused by long-term immersion in seawater.The main research contents are as follows:（1）A simple and universal strategy to construct robust and anti-biofouling amidoxime aerogels for enhanced uranium extraction from seawaterIn this study,a facile one-step process is designed to massively construct robust and anti-biofouling poly（amidoxime）aerogels（Anti-PAO gels）for highly efficient uranium extraction.The gels display porosity,large surface area,flexibility,excel ent mechanical strength to withstand the crash of the waves benefitting from the adhesive antibacterial compounds and the tight covalent bonding between the antibacterial compounds and PAO molecules,and the adsorption capacity reaches up to 1013±9.7 mg g^-1 in the 8 ppm uranium spiked solution.Significant inhibition zones are observed around the Anti-PAO gels,the adsorption amounts in bacteria-contained seawater reach 90.67%-94.82%of that in sterilized seawater,indicating the beneficial antifouling effects of the prepared aerogels for uranium extraction,providing an excel ent extraction capacity of 9.29±0.59 mg g^-1 after a 30-day field test in natural seawater.More importantly,this developed strategy possesses universal applicability,and it can be used in other amidoxime molecules and other forms of uranium adsorbents to prepare the antifouling aerogels and fibers.Together with the economic analysis results,we believe that the developed amidoxime aerogels are promising in the industrialized uranium extraction from seawater.（2）Robust and anti-adhesive polypeptide conjugated natural fiber membranes for fast uranium recovery from seawater and nuclear wasteIn this study,egg membrane（ESM）was used as the substrate material,and 2-aminobenzylamine oxime（NH₂-AO）and glutathione（GSH）were grafted onto the surface of ESM through Schiff base reaction and Michael addition reaction to obtain high mechanical strength and high uranium absorption efficiency,and anti-adhesive adsorbent（Anti-ESM/NH₂-AO）.The adsorbents not only have a porous fiber structure,but also have very good flexibility,with a tensile strength of 8.8 MPa.In the 8 ppm uranium spiked solution,92.3%of the adsorption can be completed in 4 hours,and the equilibrium adsorption capacity is 404.26±3.89mg/g.GSH provides good hydrophilicity and anti-bacterial adhesion performance of the samples.The seawater flux of the adsorbent is 7834.39 L/h·m².After three seawater cycles,the flux recovery rate（FRR）remains above 95%;the bacteria-containing seawater rarely affects the uranium adsorption of the samples;at the same time,the SEM images intuitively exhibit the anti-bacterial adhesion performances.In addition,the samples have good selectivity and reusability（can be recycled 10 times）.In the wastewater containing uranium,the residual uranium contents of the solutions after adsorption of Anti-ESM/NH₂-AO are less than 30 ppb,which meets the discharge standard.More importantly,this method is simple,making it possible to massively extract uranium from seawater.