Preparation And Properties Of Modified MOF/Cellulose Composite Membranes

Cellulose is the most widely distributed organic material in the world.With excellent hydrophilicity and biocompatibility,and safe and non-toxic,cellulose membranes offer advantages that cannot be replaced by industrial polymer membranes.However,bioactive substances can accumulate on the surface of cellulose membranes and cause biological contamination,which limits the use of cellulose membranes and therefore there is an urgent need to develop a cellulose membrane with antimicrobial properties.Metal-organic frameworks（MOFs）materials are crystalline porous coordination polymers with high selectivity,high specific surface area and excellent thermal stability,making them a potential platform for physical sterilisation with properties such as their rich variety and excellent biocompatibility.The thesis research provides new ideas for the preparation of cellulose membranes,offering a new strategy for broad-spectrum sterilisation in many biomaterial applications.It is shown that Ag/UiO-66-NH₂@BCM has good antibacterial properties and is effective in enhancing the performance of cellulose membranes,as well as in removing metal ions from water.Firstly,in this thesis,UiO-66-NH₂ with Zr as the metal centre,H₂BDC-NH₂ as the ligand and DMF as the modifier was synthesised by hydrothermal synthesis and loaded with Ag ions with antibacterial properties to prepare a novel MOF material with antibacterial properties（Ag/UiO-66-NH₂）.The Ag ion content was adjusted to explore materials with optimal antibacterial properties.The results show that silver ions can be successfully loaded onto UiO-66-NH₂ without changing the crystal structure of UiO-66-NH₂.It shows a slight decrease in thermal stability,an increase in specific surface area and pore volume,and strong antibacterial properties against both E.coli and S.aureus.The best antibacterial effect of Ag/UiO-66-NH₂ was obtained when the mass fraction of silver ions was 4 wt.%.Secondly,the thesis used the phase conversion method to prepare Ag/UiO-66-NH₂@BCM with high water flux,high retention and good hydrophilic properties by blending 4 wt.%Ag/UiO-66-NH₂ with BC.The results showed that the ultrafiltration performance of all membranes was improved after BC was blended with Ag/UiO-66-NH₂.The best ultrafiltration performance was achieved when Ag/UiO-66-NH₂ was added at 1 wt.%.Its pure water flux increased from 411.79 LMH to 541.12 LMH,retention of BSA increased from 76.8%to 99.6%,and water flux recovery increased from 68.57%to 97.36%.Its antibacterial performance reached 98%and its hydrophilic properties were also significantly improved.Finally,the thesis investigates the adsorption capacity of Ag/UiO-66-NH₂ and Ag/UiO-66-NH₂@BCM on Pb²⁺,Cd²⁺and Cr⁶⁺ions in the water column.The effect of adsorption parameters such as MOF content,contact time and initial concentration of metal ions on metal ion adsorption was additionally investigated in the thesis.In the treatment of cellulose membranes,the thesis investigated the effects of MOF concentration,metal ion concentration,contact time and temperature on the metal ion removal rate.The results showed that at a contact time of 3 h,an initial ion concentration of 50 mg/L,a temperature of 25℃and pH values of 6(Pb²⁺and Cd²⁺)and 3(Cr⁶⁺),the adsorption order of Ag/UiO-66-NH₂@BCM for Pb²⁺,Cd²⁺and Cr⁶⁺was Pb²⁺>Cd ²⁺>Cr⁶⁺and the maximum monolayer adsorption amounts were 405,390 and 328 mg/g,respectively.