Synthesis And Phosphorus Removal Performance Of Functionalized MOFs-Based Materials

Phosphorus is one of the important nutrients for animal and plant life,and is also a non-renewable mineral resource.However,with the continuous development of the economy,such as urbanization,industrialization,and agricultural intensification,a large amount of phosphorus containing wastewater is discharged into the body of water.When the concentration of total phosphorus in body of water exceeds 20μg/L,it can cause eutrophication,leading to the proliferation of harmful algae and the deterioration of water quality,thereby posing a serious threat to aquatic animals,plants and human health.Therefore,water eutrophication has become one of the water environmental pollution issues of global concern.At present,adsorption is considered an effective method for phosphate removal due to its advantages of simple operation,low economic cost,and high efficiency.In addition,the fabrication of adsorbent is the key.Among many adsorbents,metal-organic frameworks（MOFs）have attracted considerable attention in the field of phosphorus removal due to their high specific surface area,adjustable pore structure,and high thermal stability.However,previous studies have found that pure MOFs materials have some problems in phosphorus removal,such as low adsorption capacity and poor selectivity.Therefore,in this thesis we synthesized three functionalized MOFs-based materials using different modified methods,characterized the characteristics of these materials,explored phosphorus removal performance and adsorption mechanism,and discussed the influencing factors and recycling times.The main research contents are as follows:（1）MgAl-LDH@ZIF-8 composite with multi-component complementary advantages was synthesized by using the in-situ growth method.The composite material has more active sites and large specific surface area,thereby improving the phosphate adsorption performance.The MgAl-LDH@ZIF-8 adsorption capacity（70.08 mg P/g）is higher than that of ZIF-8（63.85 mg P/g）and MgAl-LDH（40.0 mg P/g）.The main adsorption mechanisms are electrostatic interaction,ion exchange and ligand exchange.The simulated wastewater adsorption experiment results show that the phosphorus removal adsorbent has practical application potential.（2）A guanidine functionalized GBA-UiO-66 material with defects was prepared through a ligand regulation strategy,which can adsorb phosphate efficiently and selectively.The GBA-UiO-66-5 material synthesized at a molar ratio of 5:5 has the best adsorption performance for phosphate,and the maximum adsorption capacity is up to 126.58 mg P/g.It has stable adsorption performance over a wide p H range and is not affected by coexisting ions.Therefore,GBA-UiO-66-5 is an efficient and selective phosphate removal adsorbent.（3）Gd-UiO-66 materials were prepared by the gadolinium（Gd）doping strategy.The Gd³⁺doping provided more metal sites,thereby enhancing adsorption capacity.The phosphate adsorption capacities of Gd-UiO-66 with different gadolinium doping amounts were higher than that of UiO-66.In addition,the optimal doping ratio of Gd³⁺:Zr⁴⁺=1:1,and the maximum adsorption capacity is 123.76 mg P/g.Furthermore,this material has a high adsorption capacity for phosphate over a wide p H range.Therefore,Gd-UiO-66 is an effective adsorbent for phosphate removal.