Study On The Adsorption Performance Of MOFs-derived Nanoporous Carbon To Removal Of Pollutants In Water

In recent years,water pollution has become an increasingly serious social problem in worldwide.Removal of heavy metal pollutants from water bodies and removal of biologically toxic endocrine disrupting hormones?EDCs?have been a difficult and hot topic in the field of water treatment research.Metal-organic framework?MOF?-derived porous carbon has attracted the attention of scholars around the world as a new type of adsorbent material that can combine the structural advantages of MOFs materials with the adsorption properties of carbon materials.To this end,two kinds of MOF-derived porous carbons were synthesized for the purpose of adsorbing and removing heavy metal pollutants and EDCs in water and tests the adsorption performance to explore the adsorption mechanism.The specific research results are as follows:?1?It has been demonstrated that MOF-based carbon materials can be used to remove contaminants in deionized water.However,the shrinkage and collapse phenomenon of the original structure of MOFs during the heat treatment process,which makes the prepared porous carbon pores block and the specific surface is not high enough,causes the adsorption performance and removal efficiency of pollutants in the water body,especially EDCs.Herein,based on the sodium chloride molten salt-assisted pyrolysis method,ZIF-8 was used as the precursor to successfully synthesize the hierarchical porous carbon composites?HCCs?composed of carbon nanosheets and carbon nanopolyhedrons.Two different EDCs?CBZ and 4-NP?are selected to compare the adsorption performance for different contaminants with carbon polyhedron?CPs?obtained by direct carbonization of ZIF-8 and commercial activated carbon and evaluate effect of temperatures,pH and tap water in adsorption.The adsorption experiments showed that the adsorption of CBZ and 4-NP by HCCs accorded with the Langmuir adsorption model.The maximum adsorption capacities were 202.5 mg·g^-1and 225.62 mg·g^-1,respectively.The HCCs had amazing adsorption rates,up to 50.63mg·g^-1·min^-1.56.405 mg·g^-1·min^-1,which is 10.7 times and 1.5 times that of commercial activated carbon,respectively.The processes of adsorption of CBZ and 4-NP by HCCs are spontaneous exothermic,but the change of temperature and pH has little effect on adsorption performance.Finally,the results of fixed bed experiments show that HCCs is able to treat up to 10,000 bed volumes of 10 mg·L^-1CBZ and 4-NP in tap water solution,respectively.It is proved that HCCs can be used as an excellent household tap water purifier filler.?2?Lead?II?ions are the most common and extremely harmful heavy metal contaminant.Lead ions are difficult to treat and selectively recycle,making them easy to enrich in the environment and eventually enter the human body.Here,we prepared Fe?III?-MOF-5 as precursor,the composite magnetic porous carbon material of ZnFe₂O₄/C was prepared by high temperature carbonization and alkaline liquid selective etching.The results show that the selective etching of alkali can effectively remove ZnO,the original carbonized products.And prepared material has a good pore structure.The results of adsorption experiments show that the magnetic porous carbon material exhibits good adsorption performance for Pb?II?ions in water and the maximum adsorption capacity is 117.5 mg·g^-1.In addition,the interference experiment results show that the porous carbon material can selectively adsorb and remove Pb?II?ions.Pb?II?ions were adsorbed on ZnFe₂O₄/C adsorbent by analyzing the change of chemical environment on the surface of the magnetic porous carbon material before and after adsorption.Finally,the magnetic porous carbon has good recycling performance.After three adsorption cycles,the adsorption capacity retention rate is as high as 84.5%,and the ZnFe₂O₄/C can be quickly recovered by the external magnetic field.