Fabrication And Performance Study Of Double-Network Hydrogel With High-Efficient Uranium Adsorption Capacity

Recovery of uranium from seawater is a key project to ensure the long-term consumption of nuclear power in China.Although hydrogel adsorbents are very ideal uranium adsorbents,it is still difficult to achieve both strong mechanical properties and high uranium adsorption efficiency of them.To deal with this unavoidable key problem for uranium extraction from seawater,a novel double-network hydrogel adsorbent has been designed in this paper.This double network hydrogel has much higher mechanical strength than that of existing hydrogel-based uranium adsorbents;superhydrophilic nanomaterials(or electrolyte polymers)and hydrogels hydrophilic network also endures the amidoximefunctional groups in the hydrogel with high-efficient and rapid uranium extraction ability.On this basis,the introduction of antibacterial properties can further improve its uranium adsorption performance in natural seawater.More importantly,this kind of hydrogel has cheap raw materials and simple synthesis process,which is convenient for industrial production.This study will provide a highly efficient for large-scale seawater uranium and cheap new hydrogel-based uranium adsorbent,and also will inspire the design and fabrication of new high-efficient hydrogels and even other types of adsorbents to accelerate the industrialization of the uranium extraction from seawater.This work has a feasible application prospect and important scientific significance.The main research contents:(1)We have designed and fabricated a new nano-clay-polyamidoxime(NC-PAO)high strength double network(DN)composite hydrogel adsorbent with high-efficient uranium adsorption performace.By introducing a small amount of nano-clay(magnesium aluminum silicate RDS nano-sheet)to improve the hydrogel hydrophilicity,so that the amidoxime functional group in the hydrogel is in a more hydrophilic microenvironment,and then significantly improve the uranium adsorption performance of the hydrogel adsorbent.In the16 ppm U-spiked simulated seawater for 48 h,the uranium adsorption capacity of this hydrogel can reach 465 ± 27 mg/g.This DN structure of NC-PAO DN hydrogel can provide a largely enhanced mechanical property,on account of the double-network synergistic effect between the crosslinked gelatin soft network and crosslinked cel ulose nanofibers(CNF)hard network.This NC-PAO DN hydrogel has a strong mechanical property,and its tensile strength can reach 2.42 MPa,which can be kept almost unchanged after 10 adsorptiondesorpton circles.As a result,this NC-PAO DN hydrogels can reach 8.62 mg/g in seawater after filtering bacteria for only 25 days,and the average adsorption rate can reach 0.345mg/(g·day).(2)On the basis of the research in the previous chapter,an antimicrobial double network uranium adsorbent for hydrogels was designed in view of the damage caused by various bacteria and microorganisms in natural seawater.The antimicrobial and super-hydrophilic polyhexagenetformin can directly crosslinked the PAOs to form a soft cross-linking network,which gives the hydrogels excel ent antibacterial and enhanced uranium extraction performance.In addition,the dual network structure formed by the combination of the soft network and the hard polyethylene glycol cross-linked network also enables the hydrogel to have strong mechanical properties(the tensile strength can be up to 4.37 MPa).In 16 ppm uranium-enriched seawater for 48 h,the adsorption capacity can reach 384 ± 28 mg/g.Consequently,after 25 days of uranium extraction from natural seawater containing diverse bacteria and microorganisms,the uranium extraction capacity can reach 9.56 mg/g.This work provides a new idea for the design of antimicrobial high-strength hydrogels and hopes to be used for large-scale industrial uranium extraction from seawater in the future.