Study On Surface Functionalization And Drug Adsorption Of MXene

Pharmaceutical wastewater is one of the most serious environmental wastewater,therefore the searching of effective methods for treatment of the pharmaceutical wastewater is highly desirable.Among various treatment techniques,the adsorption technique has become the main method to treat wastewater owing to its simple,efficiency and low-cost.As a new family two-dimensional（2D）materials,the metal carbides,nitrides,and carbonitrides（named as MXenes）,which possess high specific surface area,unique 2D structure and rich surface functional groups and displayed high potential for applications in energy conversion and storage,catalysis,biomedicine and environmental treatment.Especially,the utilization of Mxene and MXene-based composites for adsorptive removal environmental pollutants has attracted great attention.However,the adsorption performance of unmodified MXene is normally limited due to its poor dispersibility and lack of surface functional groups.Therefore,the surface of modification of MXene to improve its adsorption performance is of great importance.In this thesis,the substrate material MXene（Ti₃C₂）was obtained by etching and intercalation.Three Ti₃C₂-based composites were fabricated through three routes,phosphazene cross-linking,Debus-Radziszewski multi-component reaction and hydrothermal treatment.The surface morphology,elements,and functional groups of these composites were analyzed by SEM,FT-IR,TGA and XPS.The anticancer agent Doxorubicin（DOX）and antibiotic tetracycline were selected as the model pollutant and the effects of contact time,p H value,initial concentration,and temperature on the adsorption behavior were studied in detail.The experimental data were fitted and analyzed by adsorption kinetics,isothermal adsorption line and adsorption thermodynamic models.The main contexts of this thesis are as follows:（1）A new type of MXene-based composite（named as Ti₃C₂-SL）was successfully prepared by coupling amino group functionalized Ti₃C₂with sodium lignosulfonate（SL）using phosphazene as cross-linkage,and its adsorption properties for DOX were studied.The maximum adsorption capacity of the original material Ti₃C₂ for DOX was 50.51mg g^-1,while the maximum adsorption capacity of the surface functionalized composite Ti₃C₂-SL was 190.78 mg g^-1.The adsorption process was a combination of physical adsorption and chemical adsorption,which was more in line with the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model.The adsorption mechanism may be the electrostatic interaction between-SO₃^-and NH₃⁺,and the physical adsorption of intraparticle diffusion on the surface of Ti₃C₂-SL.The adsorption process is a spontaneous endothermic process,and increasing temperature and p H is beneficial to the adsorption.（2）Ti₃C₂ was coupled with silane agent to introduce amino groups on the surface of Ti₃C₂.Ti₃C₂-SA was obtained through conjugation of amimo groups functionalized Ti₃C₂ and sodium alginate via Debus-Radziszewski multi-component reaction.The adsorption experiment was carried out with DOX as the model of pollutant.It was observed that Ti₃C₂-SA had good dispersion in water,and the adsorption efficiency of DOX could reach 98%.The adsorption process followed the pseudo-first-order and pseudo-second-order models,as well as the Langmuir isotherm model,indicating that the adsorption process mainly followed chemical adsorption,dominated by monolayer adsorption,and the main adsorption mechanism was electrostatic interaction.And the adsorption procedure is spontaneous exothermic process.DOX adsorption is more favorable at room temperature and alkaline solution.（3）The composite material Ti₃C₂-MIL-101（Fe）was successfully synthesized by combination of diazonium salt reaction and hydrothermal treatment.The adsorptive removal of tetracycline using Ti₃C₂-MIL-101（Fe）was evaluated in detail.Results demonstrated that Ti₃C₂-MIL-101（Fe）possesses good adsorption performance for tetracycline wastewater.The adsorption capacity can reach 193.43 mg g^-1,which is more than 9 folds as compared with that of original Ti₃C₂(21.29 mg g^-1).The particle diffusion model and Freundlich model can be well used to describe the experimental adsorption process,and the adsorption process is a spontaneous and feasible endothermic process.