Study On The Preparation And Performance Of Functionalized Covalent Organic Framework

With the development of the times,people gradually have diversified requirements for life.Energy shortage and environmental problems have increasingly become the focus of people’s attention,which is an urgent problem to be solved.Scientific researchers are making active exploration on the way forward and discover that covalent organic frameworks（COFs）are potential materials in solving these problems.Constituted by dynamic covalent bonds,covalent organic frameworks stand out from other materials with their superior crystallinity.At the same time,these materials are widely used in dye gas storage,drug delivery,heterogeneous catalysis and photocatalysis due to their low density,various synthesis methods and easy functional modification.In this paper,covalent organic framework materials were designed,synthesized and functionalized,and their performances in ion recognition,dye adsorption,solid acid catalysis and photocatalytic degradation were studied.1.A novel luminescent covalent organic framework（TBT-BP-COF）was successfully synthesized by Suzuki coupling reaction.The material can be used as a rapid and efficient luminescent probe to identify metal ions in THF solution,as well as a sustainable and easy to recover absorbent material in wastewater,showing dual functionality in application.The significant fluorescence quenching of TBT-BP-COF in the presence of Fe³⁺indicates that TBT-BP-COF has high sensitivity（6μM）and high selectivity for detaction of Fe³⁺.In addition,TBT-BP-COF had excellent adsorption capacity for neutral red dye,with the adsorption capacity was as high as 398.41 mg·g^-1.Meanwhile,the adsorption process had good correlation with pseudo-second-order kinetic model and Langmuir isotherm.After five cycles,the removal rate of neutral red dye can still reached 85%.More importantly,after quenching and releasing Fe³⁺,the material can be further used for the absorption and desorption of organic dyes.All processes are efficient,reversible and meet the requirements of new sustainable materials.This part of work will provide new ideas for the design of sustainable chemical multifunctional COF materials.2.Sulfonated materials have been used as efficient and environmentally friendly heterogeneous catalysts for the synthesis of biodiesel based on long-chain fatty acid esters.In this work,the sulfonic acid groups were grafted onto TBT-BP-COF by grafting method for functional modification,and a supported solid acid catalyst TBT-BP-SCOF with high catalytic activity was obtained.A series of experiments were carried out to compare the reation conditions,such as reaction time,reaction temperature,catalyst content and so on,to investigate the activity and stability of the catalyst.The yield of methyl dodecanoate from sulfonated material TBT-BP-SCOF reached 97.3%at room temperature and could be recycled for more than four times.Therefore,the sulfonated materials be used as one of the effective catalysts for biodiesel production.3.In this work,a photo responsive COF-TpTt material was constructed by solvothermal method using 1,3,5-Triazine-2,4,6-triamine（Tt）and2,4,6-Triformylphloroglucinol（Tp）as precursors.After functionalization,the compsite of COF-TpTt/AgI with high photocatalytic efficiency was successfully prepared by coprecipitation of COF-TpTt and AgI.Experiment selected Rhodamine B as target degradator,the photocatalytic performance and mechanism of COF-TpTt/AgI degradation of Rhodamine B were investigated.After 55 min of illumination,the degradation.rate of Rhodamine B was 100%.Scavenger experiments counfirmed thatO₂^-and h⁺played an important role in the photocatalytic process under visible light irradiation.COF-TpTt/AgI possesses good reusability,and the degradation rate can still reach 92.7%after five degration cycles.Therefore,this work fully demonstrates its application potential in the degradation of organic pollutants.