Studies On Fabrication And Uranium Adsorption From Seawater Of Poly (Amidoxime) Hydrogels

The seawater uranium extraction project is of a great strategic significance to solve the current energy supply shortage and ensure China's energy security.Various countries in the world have successively started the research on extracting uranium from seawater and have achieved many stage developments.However,the preparation of uranium adsorbents with high selectivity,high adsorption capacity and low cost is still a great challenge to be solved in the current research.This amidoxime-based adsorbent is one of the most promising adsorbents for uranium extraction from seawater,but the adsorption capacity and rate of uranium extraction need to be further improved.In this study,the poly?amidoxime?was designed to be a hydrogel membrane,and the hydrophilic 3D network of the hydrogel was used to disperse and fix the polyamidoxime polymers,so as to obtain higher uranium extraction performance,faster rate and still maintain good mechanical properties.Moreover,the fabricating process of such hydrogels is simple and low-cost,which is more conducive to mass production and will inspire for the preparation of hydrogel adsorbents containing other uranium extracting functional groups and other hydrophilic networks.This study is expected to promote the research on extracting uranium from seawater to industrial production,which has important scientific significance and great potential application value.The main contents are as follows:?1?Based on the UV-light polymerization method,we develop a simple and fast method to directly fabricate a poly?amidoxime??PAO?hydrogel membrane,which exhibits high uranium adsorption capacity.This PAO hydrogel owns semi-interpenetrating?Semi-IPN?structure and the hydrophilic poly?acrylamide?3D-network of hydrogel can disperse and fix PAOs well.As a result,the hydrogel exhibits an outstanding uranium adsorption efficiency?556 mg/g of muranium/mhydrogel in 32 ppm uranium-spiked seawater?,and after five adsorption-desorption cycles,its uranium extraction capacity can still retain 76%.Most importantly,U-uptake capacity of this hydrogel can achieve 4.87mg/g of m_uranium/m_{dry gel}within natural seawater just after 4 weeks.?2?Based on the previous research,a novel cellulose paper-polyamoxime bio-inspired composite hydrogel membrane adsorbent has been further designed and prepared,which has good antibacterial property and high strength.By compositing with super-hydrophilic cellulose paper and copolymerizing an antibacterial monomer on a polymerization network,the hydrogel film has good hydrophilicity and broad-spectrum antibacterial properties,thereby obtaining higher uranium extraction performance.In addition,the introduction of paper-based cellulose fibers also can endow the hydrogel membrane excellent mechanical property?tensile strength up to 1.10 MPa?.In 16 ppm U-spiked seawater without filtering bacteria,the uranium adsorption capacity has reached 465 mg/g,and after eight adsorption-desorption cycles,its uranium extraction performance can still retain 90.6%,while its mechanical property can remain almost unchanged.After 6 weeks of adsorption in real seawater without filtering bacteria and microorganisms,the uranium uptake capacity can reach 6.21 mg/g.