The Preparation Of Lead-imprinted Mesoporous Silica Materials Based On The Functionalization Of Pyridine Groups And The Study Of Their Adsorption Properties

Heavy metal lead ions are highly toxic and bioaccumulative,which have a long duration in the environment and seriously damage human health.Therefore,it is important to remove Pb²⁺from wastewater.At present,the methods that have been used for removal lead ions often have problems such as complicated pretreatment,high detection limit,and poor selectivity.Therefore,it is important to establish a reliable,highly sensitive and highly selective method for the separation and detection of lead ions.Ion-imprinted techniques is an experimental technique that can selectively identify specific ions.In this paper three types of functionalized lead ion-imprinted silicon materials were prepared:lead ion-imprinted mesoporous silicon materials functionalized with nitrogen-containing tridentate and sulfur-containing multidentate functional monomers.The functionalized mesoporous silicon materials were used as a solid phase adsorbents to selectively separate lead ions and combined with inductively coupled plasma-atomic emission spectrometer?ICP-AES?to realize the removal of lead ions.The detailed work were as follows:1.Theleadion-imprintedmesoporoussilicon materialsmodifiedwith nitrogen-containingtridentateligandsweredesignedandsynthesized.Dimethylpyridylamine?BPMA?and bispyridin-2-methyleneamine?DIPA?were used as functional monomers,lead ion as template and 3-chloropropyltriethoxysilane as crosslinker.The mesoporous silica materials MCM-41 were used as the solid phase carrier.The functional monomers have been successfully modified on the surface of mesoporous materials MCM-41 by infrared spectroscopy.Scanning electron microscopy,transmission electron microscopy,X-ray small angle diffraction and nitrogen adsorption desorption analysis have confirmed that the prepared materials were kept the morphology of the original mesoporous silicon.Elemental analysis indicated that BPMA-Pb-IIMS possesses a higher nitrogen content.In addition,two corresponding non ion-imprinted materials were also successfully prepared.2.Adsorption performance of lead ion-imprinted mesoporous silicon materials and the corresponding non-imprinted materials were studied.The results show that ion-imprinted materials have a significant increase in the adsorption amount and selectivity of lead ions.The adsorption isotherms and adsorption kinetics experiments show that the two imprinted materials have a large adsorption capacity and a fast adsorption rate for lead ions,and the adsorption behavior accords with the Langmuir isotherm model and the pseudo two order kinetics model.BPMA-Pb-IIMS possesses ahigheradsorptionperformanceandexcellentrecyclability.Therefore BPMA-Pb-IIMS was selected as the adsorbent material and combined with inductively coupled plasma atomic emission spectrometry?ICP-AES?to remove lead ions in industrial wastewater.The detection limit was 0.041?g L^-1,which provided an effective method for the selective separation and detection of lead ions in water.3.In view of the excellent performance of functional monomers with nitrogen atoms,the ligand containing sulfur atoms was introduced.We selected?pyridyl-2-methylene?thiocarboformamide?PYHC?as chelating ligand,Lead ion as template,3-chloropropyltriethoxysilane as crosslinker.The mesoporous silica materials MCM-41 were used as the solid phase carrier.The functional monomer or complex has been successfully modified on the surface of mesoporous materials MCM-41 by infrared spectroscopy.The adsorption properties of the materials were investigated.The isothermal adsorption model,adsorption kinetics curve and cycle performance were studied.Compared with the previous tridentate monomer functionalized lead imprinted materials,the adsorption capacity of multidentate functionalized lead imprinted materials PYHC-Pb-IIMS were better.