Preparation Of Biomass-Based Materials And Their Adsorption And Antibacterial Properties On U(Ⅵ)/Cr(Ⅵ)

In this study,using dialdehyde waste paper（DAWP）as a cross-linking agent to immobilize persimmon tannin（PT）which is first used to remove the U（Ⅵ）and Cr（Ⅵ）via the“waste control by waste”concept.At the same time,persimmon tannin acid（PT）and amino-functionalized MXenes（MXenes-NH₂）are introduced into the dialdehyde cellulose nano-fibers（DACNF）by crosslinking reaction,and a biosorbent DACNF-MXenes-NH₂-PT is prepared for the removal of U（Ⅵ）and Cr（Ⅵ）.The microscopic and macroscopic surface properties of the adsorbent are characterized by advanced characterization techniques,and the effects of variable p H,coexisting ions and equilibrium time on the removal process are investigated by batch experiments,and their inhibitory properties on E.coli were explored.The results are as follows:（1）Advanced characterization technology confirmed the presence of aldehyde groups on the surface of DAWP-PT,redox reaction to U（Ⅵ）and Cr（Ⅵ）,and DACNF-MXenes-NH₂-PT has a fibrous structure,abundant active groups（Ti-OH,Ar-OH and-NH₂）,and high chemical stability.（2）The maximum removal rates of DAWP-PT to U（Ⅵ）and Cr（Ⅵ）were 242.3mg/g（p H=6.0）and 178.7 mg/g（p H=2.0）,respectively,at 298 K,which is competitive with most reported solid materials;The water environmental conditions play an important role in the removal process for DACNF-MXenes-NH₂-PT,and DACNF-MXenes-NH₂-PT has higher absorption of U（Ⅵ）（105.7 mg/g）and Cr（Ⅵ）（82.8mg/g）.At the same time,equilibrium studies show that the adsorption data follow the Langmuir and pseudo-second-order models,which indicates that single-molecule adsorption and homogeneous chemisorption dominate the removal process.（3）SEM-EDX,DFT and XPS analysis show that the adsorption of U（Ⅵ）by DAWP-PT was mainly through surface complexation,while the elimination of Cr（Ⅵ）was a redox reaction process,and about 65.33%of Cr（III）and 34.67%of Cr（Ⅵ） coexisted on the surface of DAWP-PT;The characterization of DACNF-MXenes-NH₂-PT shows that the elimination of radionuclides mainly depended on the strong coordination,complexation and synergy of surface adsorption and intercalation adsorption.（4）The competitive adsorption study finds that the removal efficiency of Cr（Ⅵ）by DAWP-PT decreased slightly compared with that of a single system,and the removal rate of U（Ⅵ）is lower than that of Cr（Ⅵ）.DACNF-MXenes-NH₂-PT has a selective affinity for U（Ⅵ）,but its removal rate decreases slightly after three adsorption-desorption cycles.（5）Escherichia coli is cultured by agar and different amounts of the biosorbent DAWP-PT are added to study its inhibitory ability against Escherichia coli.Compared to the parallel groups,it is found that the more DAWP-PT content was added,the lower the activity of E.coli.