Synthesis Of Functionalized Mesoporous Adsorption Materials And Their Adsorption Properties Of Heavy Metal Ions

This paper is based on the experimental investigation of heavy metal ions in the environment caused by pollution and its great harm to human beings.It mainly deals with pre-processing problems encountered in the analysis and detection of heavy metal ions in large-scale analytical instruments.Recently,researchers have used functionalized ordered mesoporous materials as novel adsorbent materials for the separation and enrichment of heavy metal ions,by inserting new functional groups on the basis of ordered mesoporous materials MCM-41.The modification was performed to obtain a functionalized adsorption material with specific adsorption properties,and a large-scale analytical instrument?ICP-AES?was used to examine the adsorption properties of the adsorbent material for heavy metal ions to establish new ones.The functionalized mesoporous adsorbent material assisted ICP-AES for heavy metal ion separation detection method is of great significance for the adsorption and separation of heavy metal ions and the establishment of an efficient and accurate analytical method.The main contents of this paper are as follows:?1?Three novel functionalized mesoporous silica adsorbents were prepared and used f or the analysis of adsorption performance of heavy metal ions?Cu???,Pb???,Cr????.By referring to the relevant literatures,three nitrogen-containing functional ligands?4-?dihydro-1-pyrazole??methylphenol?DPP?,4,7-dihydroxy-1,10-phenanthroline?DHP?,2?2-pyridyl?methan ol?DPM?were designed and prepared,then three nitrogen-containing functional ligands we re grafted in an ordered manner by the action of 3-isocyanatopropyltriethoxysilane?TEPIC,silane coupling agent?.Three functional mesoporous silica adsorbents?DPP@MCM-41,D HP@MCM-41,DPM@MCM-41?were obtained on the surface of the pore material MCM-41,and through a series of characterizations?FI-TR,SEM,TEM,XRD,EDS,BET?it wa s demonstrated the successful loading of the functional monomer and retained the original morphology of the mesoporous material MCM-41.The adsorption results of heavy metal i ons?Cu???,Pb???,Cr????by three functionalized mesoporous adsorptive materials DPP@MCM-41,DHP@MCM-41,and DPM@MCM-41 showed that the pH value of maximum a dsorption of Cu???ions was 6.the adsorption capacity for Cu???ions were 62.8 mg/g?72.5 mg/g?76.8 mg/g,at pH=6,25?;the adsorption capacity for Pb???ions was 153.3mg/g?116.2 mg/g?190.9 mg/g,at pH=6,25?;The adsorption amount of Cr???ions were 73.6mg/g?28.8mg/g?108.3 mg/g,at pH=5,25?.Compared with the original MCM-41 mesoporous materials,the modified mesoporous adsorbent has improved the adsorption capacity of heavy metal ions?Cu???,Pb???,Cr????.?2?Combined surface imprinting technique with Cr???ions as template ions,2?2-pyridyl?methanol?DPM?as functional monomer,3-isocyanatopropyl triethoxysilane?TEPIC?as silane coupling agent,Chromium???imprinted mesoporous adsorbent?Cr???-?Ps?and non-imprinted mesoporous adsorbent NIP were prepared and used for selective adsorption of Cr???ions.The results of adsorption experiments showed that the adsorption amount of Cr???ion-immobilized materials?Cr???-?Ps?for Cr???ions were 151.2 mg/g at 25°C and pH=5,about 1.4 times of mesoporous adsorption material?NIP?,and the functionalized adsorption material prepared under this condition had no obvious adsorption effect on Cr???ion in solution.It is showed that the ion-immobilized materials?Cr???-?Ps?can be used for Cr???and Cr???ions selective separation.?3?Adsorption kinetics of Cr???ions in solution was investigated using self-prepared chromium???imprinted mesoporous adsorptive materials?Cr???-?Ps?,and the adsorption property of Cr???ions by imprinted materials was found.It is a rapid process,the adsorption kinetics curve is in good agreement with the pseudo-second-order kinetics model?R²=0.9806?,the adsorption process is mainly chemical adsorption,and the isothermal adsorption model is more in line with the Langmuir adsorption isotherm model?R²=0.9929?.The adsorption of Cr???ions by chromium???imprinted mesoporous adsorptive materials?Cr???-?Ps?was mainly monolayer adsorption,and the theoretical saturated adsorption capacity Q_max was 163.9 mg/g calculated by Langmuir equation,consistent with the actual adsorption capacity of 151.2 mg/g.It is indicates that the synthesized bipyridine-functionalized chromium???imprinted mesoporous adsorption material has faster adsorption kinetics and higher performance than traditional materials.?4?The method established in this paper was applied to the detection of extracts from actual metal samples.Combined with the method validation procedure,the detection limit of this method was 0.0270ug/mL and the limit of quantitation was 0.0361ug/mL.The spiked test of the actual metal sample leaching solution showed that the recovery of Cr???was between 96.8%and104.6%,RSD was between 0.3%and 1.1%,and the Cr???recovery was between 99%and 101%,RSD was between 0.2%and 1.1%.It shows that this method has good accuracy and can be used for the analysis of actual samples.