Preparation And Modification Of Imine Type COF Adsorbent And Study On Adsorption Properties And Mechanism Of Typical PPCPs

In recent years,the pollution caused by drugs and personal care products（PPCPs）to the water environment and natural resource ecosystem in the surrounding area is increasingly serious,which has aroused widespread concern in the society.PPCPs exist in harsh water environment for a long time,which will pose a huge potential threat to our life,health and water environment safety.Adsorption technology has been widely used in the removal of organic pollutants in water environment because of their three characteristics and advantages of simple operation,renewable adsorbent and no direct secondary pollution after long-term use.At present,covalent organic frameworks（COFs）have attracted much attention because of their excellent characteristics such as large specific surface area,stable structure and adjustable structure function.However,COFs still has some disadvantages,such as harsh preparation conditions and poor adsorption sites,which to some extent limit its application in the adsorption of environmental pollutants.This paper intends to form two kinds of imine type COFs through the condensation reaction of amine-aldehyde using a simple solvon-thermal method.The former uses sulfonic acid group for post-modification to improve the adsorption performance of PPCPs,while the latter uses the hydrogen bond between the nitrogen elements rich in its structure and the pollutants to promote the adsorption of PPCPs.The specific contents and results are summarized as follows:（1）TAB-DVA-COF was synthesized from 2,5-divinyl-1,4-benzaldehyde and1,3,5-tri（4-aminophenyl）benzene by amine aldehyde condensation reaction,and modified by sulfonic acid group,a new type of COF-SO₃H adsorbent was synthesized.X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）and field emission scanning electron microscopy（SEM）and other characterization techniques were used to explore the morphological characteristics and spatial structure characteristics of the materials.Studies have shown that COF-SO₃H has a strong affinity for the 13 drugs studied in this paper,especially for diclophenic acid（DCF）.Its maximum adsorption capacity for DCF is 770 mg/g,9.3 times that of commercial activated carbon（AC）,1.5 times that of GO,and 3 times that of 18%SO₃-Ui O-66.After further data analysis,it can be clearly seen from the research results that the adsorption isotherm data were in good agreement with the Langmuir model,and the adsorption kinetics study followed the basic second-order kinetics model.Thermodynamic values,ΔH°<0 andΔG°<0 indicates that the reaction with adsorbents is a spontaneous exothermic chemical process.In addition,various characterization methods were used to verify that the adsorption mechanism of COF-SO₃H on DCF mainly consisted ofπ-πinteraction and hydrogen bonding.（2）A new PyTTA-Dva-COF adsorbent was successfully prepared by a simple solvent-thermal synthesis method.XRD,SEM,FT-IR were used to study the surface morphology and structural characteristics of the adsorbent.The results showed that PyTTA-Dva-COF had uniform nanofiber structure,rich and strong C=N functional groups,and high chemical stability.At room temperature,the saturated adsorption capacity of PyTTA-DVA-COF for bisphenol A（BPA）is 285 mg/g,and the adsorption reaction process satisfies Langmuir isothermal model.The kinetic data are consistent with the basic second-order kinetics model and the thermodynamic parametersΔG°<0andΔH°<0,indicating that the adsorption is a spontaneous exothermic process.PyTTA-Dva-COF showed consistent adsorption capacity for BPA under different p H values.In addition,the effect of water quality on adsorption and the regeneration ability of adsorbent were investigated,and it was proved that the adsorbent has good environmental application potential.In addition,it has been proved thatπ-πinteraction and hydrogen bonding are the main factors for the adsorption of BPA.