Design And Synthesis Of Phloroglucinol-based Porous Aromatic Frameworks And Their Adsorption Of Organic Micropollutants In Water

In recent years,Porous Aromatic Frameworks(PAFs),as a new class of porous materials,have shown excellent modifiability and stability due to their unique aromatic building units and carbon-carbon bond linkages of their frameworks.Because of these advantages,it has been widely applied in the fields of gas adsorption and separation,catalysis,sensing and removal of pollutants.In particular,in the field of wastewater treatment which matters the sustainable development of environment,PAFs have shown their unique application advantages.PAFs with suitable adsorption sites and highly connected channels can be used for absorbing pollutant in water efficiently by well design and modification.Meanwhile,due to the strong acid and alkaline environment prevailing in wastewater,the excellent stability of PAFs has become an important prerequisite for its application in wastewater treatment.This work is devoted to the adsorption study of the important organic micropollutants in water environmental pollution control.Based on the characteristic that organic micropollutants generally contain polar functional groups,we designed and synthesized phloroglucinol-based porous aromatic frameworks.The adsorption property of the material to the typical organic micropollutants in water was studied by adjusting the pore size and the surface wettability of the material.In this work,using sonogashira-hagihara reaction,we successfully synthesized three phloroglucinol-based porous aromatic frameworks(PAF-80,PAF-81 and PAF-82)by combining various alkynyl structural units and phloroglucinol based structural units.The structure characteristics of the hydroxyl-functionalized skeleton can be proved by infrared spectroscopy,and the water contact angle test also shows that it has good hydrophilicity.We investigated the adsorption performance of the three PAFs on three typical pollutants,and the kinetic test results showed that PAF-82 was the fastest among several materials.For bisphenol A and 2-naphthol,PAF-82 can reach adsorption equilibrium within 15 minutes and 30 minutes,with removal efficiency of 99% and 97%,respectively.It has the fastest removal efficiency for p-chloro-xylenol,and the adsorption equilibrium can be reached within 10 minutes,achieving a removal efficiency over 99%.PAF-82 has considerable adsorption capacity for this kinds of pollutants.Based on the study of isothermal adsorption experiments,the maximum adsorption capacities of PAF-82 for organic micropollutants such as bisphenol A,2-naphthol and p-chloroxylenol were 689 mg/g,431 mg/g and 480 mg/g,which fitted by Langmuir adsorption model according to isothermal adsorption equation.In addition,PAF-82 has excellent recyclability and stability,which can maintain excellent removal performance after 5 regeneration cycles.It is found that the synthesized phloroglucinol-based PAF is an effective adsorbent for organic micropollutants in wastewater.In order to further improve the adsorption rate of PAFs for adsorbates,we proposed a strategy for the synthesis of PAFs with the participation of template molecules.Using the target pollutant molecule bisphenol A as the template,we successfully synthesized a new templateguided PAFs(PAF-T-2)by adding template molecules to the synthesis system,which achieved the purpose of regulating the channel properties of PAFs.The adsorption rate of PAF-T-2 for bisphenol A has been significantly improved compared with PAFs without template control.The kinetic test showed that PAF-T-2 could increase the removal efficiency of bisphenol A from 77% to 98% within 30 s.In addition,isothermal adsorption experiments confirmed that the adsorption capacity of the material also increased to a certain extent(689 mg/g to 800 mg/g).Studies have shown that the introduction of template molecules has successfully regulated the adsorption properties of PAFs.