Preparation Of Ti₃C₂T_x MXene-based Functional Materials And Their Application On The Detection Or Adsorption And Removal Of Typical Pollutants In Water

Water pollutants mainly include heavy metals,synthetic dyes,antibiotic,etc.They exist stably in water and pose a serious threat to the environment and human health.Therefore,effective monitoring and control of water pollution is of great significance for ecological environment protection.This thesis synthesized a series of Ti₃C₂T_x MXene based functional materials by changing the preparation method of Ti₃C₂T_x MXene,surface modification of Ti₃C₂T_x MXene,or fabrication of Ti₃C₂T_x MXene-based composites,and then explore their applications in detection or adsorption and removal of typical pollutants in water.The main research content is as follows:（1）Ti₃C₂T_x MXene/graphite oxide（GO）three-dimensional porous aerogel（MGA）was prepared by hydrothermal method and freeze-drying treatment technology.The Ti₃C₂T_x MXene,MGA and MGA/Ag I composites were characterized by scanning electron microscope（SEM）,X-ray diffraction（XRD）and UV vis DRS,which proved the successful preparation of MGA and MGA/Ag I.Optimizing the photoelectrochemical（PEC）performance of MGA by adjusting the original feed ratio of Ti₃C₂T_x MXene to GO:When the feed mass ratio of Ti₃C₂T_x MXene to GO is 1:8,the MGA(denoted as MGA_1:8)obtained by modifying the electrode exhibits the strongest photoelectric response signal.The three-dimensional porous structure of MGA_1:8 not only avoids the stacking of Ti₃C₂T_x MXene layers,but also avoids the aggregation of Ag I particles as photosensitizers and recognition elements on its surface.MGA_1:8 can form a type II heterojunction with Ag I,reducing the recombination rate of electron hole pairs and effectively improving the sensitivity of the sensor.PEC sensor constructed based on MGA_1:8/Ag I exhibits good response to H₂S in the linear range of 5 n M-200μM,with a detection limit of 1.54 n M（S/N=3）.This sensor has good selectivity and stability,providing a new approach for the detection of H₂S in water,and has potential application prospects.（2）Preparation of Ti₃C₂T_x MXene with different fluorine content by etching Ti₃Al C₂ with different concentrations of hydrofluoric xcid（HF）.The etched products were characterized by XRD,SEM,and X-ray photoelectron spectroscopy（XPS）,demonstrating the successful preparation of Ti₃C₂T_x MXene.The adsorption experiment of tetracycline in water was conducted using Ti₃C₂T_x MXene with different-F contents.It was found that the Ti₃C₂T_x MXene（MX-10）prepared with 10%HF had the maximum adsorption capacity and could effectively adsorb tetracycline in the p H range of 1-9.This proves that MX-10 has a wide p H range and can be used for the adsorption and removal of tetracycline in strong acid to weak alkaline water bodies.The experiments of adsorption kinetics,adsorption thermodynamics and adsorption isotherm prove that the adsorption process of MX-10 for tetracycline belongs to chemical adsorption,and the maximum adsorption capacity can reach 903.4 mg/g.In addition,after five cycles of testing,the adsorption performance of MX-10 can still reach 80%of its maximum adsorption capacity,which is beneficial for recycling.This study provides a new approach for the adsorption and removal of tetracycline in water bodies.（3）Carboxylated Ti₃C₂T_x MXene（COOH-Ti₃C₂T_x）was obtained by one-step carboxylation treatment of Ti₃C₂T_x MXene.Based on the bond between carboxyl group in COOH-Ti₃C₂T_x and amino group in chitosan（CS）,COOH-Ti₃C₂T_x/CS gel beads（TCCS）were prepared.The successful preparation of TCCS was demonstrated through XRD and Fourier transform infrared spectroscopy（FTIR）.N₂ isotherm adsorption desorption curve（BET）and SEM characterization proved that the addition of COOH-Ti₃C₂T_x could effectively increase the specific surface area and surface roughness of gel beads.The TCCS（denoted as TCCS-10）prepared at a feed mass ratio of10:1 between CS and COOH-Ti₃C₂T_x exhibits the most excellent adsorption performance for Hg²⁺.By comparing the adsorption performance of CS and TCCS-10 for Hg²⁺in water under different p H conditions,it was demonstrated that the presence of COOH-Ti₃C₂T_x effectively increases the acid stability of TCCS-10.Studies on adsorption kinetics,adsorption thermodynamics and adsorption isotherm show that the adsorption process of TCCS-10 for Hg²⁺belongs to chemical adsorption,and the maximum adsorption capacity is up to 1190.2 mg/g.According to XPS analysis,the excellent adsorption performance of TCCS-10 on Hg²⁺is attributed to the complexation of hydroxyl,carboxyl,amide and other functional groups with Hg²⁺.In addition,the adsorption anti-interference and cyclic performance of TCCS-10 were studied,demonstrating that TCCS-10 has good selective adsorption of Hg²⁺,and its adsorption capacity remains at 94.2%after 5 cycles of use.This study provides a new adsorbent for the adsorption and removal of Hg²⁺from water,which has advantages such as easy recovery,recyclability,and no secondary pollution.