Heavy Metal Ion Imprinted Polymers: Synthesis,Characterization And Performance Studies

In recent years,heavy metals contamination has worsened,which has caused serious environmental problems and widespread attention.It is easily enriched and refractory,and it have been confirmed as the threats to human health even at very low concentrations.Ion imprinting technology?IIP?has a broad development prospect due to its predictability,high practicality and specificity.It is innovative to combine the ion-imprinting technology with different functional materials and take advantage of their respective preponderances to prepare new composite materials that can quickly,efficiently,and specifically recognize heavy metal ions.The research results are summarized as follows:1.Introducing quantum dots of fluorescent materials?QDs?.A new fluorescent imprinted polymer is prepared by combining the good water solubility,biocompatibility,low toxicity,and excellent fluorescence characteristics of QDs with high sensitive and selective ion imprinting technology.It makes full use of the specific identification and selective capacity of ion imprinted polymers and the excellent fluorescent properties of QDs,which can more accurately and efficiently identify the target ion,and achieve rapid and sensitive detection of Fe???in complex sample matrices.A new composite SiO₂@QDs@Fe-IIP with higher specificity,sensitivity and stability has been successfully prepared via a surface imprinting technique,with SiO₂nanoparticles as the support carrier,Mn-Zn S QDs as the light-emitting material,and Fe???as the template ion.The morphology and structure of SiO₂@QDs@Fe-IIP was characterized by fourier transform infrared?FT-IR?,scanning electron microscopy?SEM?,and diffraction of x-rays?XRD?,which is correspond to each other.The optimum conditions to SiO₂@QDs@Fe-IIP for Fe???at concentration 25mg/L,p H8.0 and response time 35min.Its fluorescence intensity varies linearly with the concentration of Fe???in the range 2-50?mol/L and the detection limit is2.229nmol/L.Compared with other interfering ions,the relative selectivity coefficient of SiO₂@QDs@Fe-IIP to Fe???is 2.313,which has high selective recognition ability.In practical applications,the recovery of Fe???in tap water by SiO₂@QDs@Fe-IIP is as high as 96.51%.2.Introducing metal-organic framework materials?MOFs?.A new imprinted polymer with more and uniform recognition sites is prepared by utilizing the high porosity,large specific surface area and flexible binding functional groups of MOFs and the high specificity of ion imprinting technology.The functional structure is designed to more accurately and efficiently identify Hg???,and realized the trace detection of Hg???.In this paper,the metal-organic framework material MOF-199 was synthesized by solvothermal synthesis method with Cu?N0₃?₂·3H₂0 as the center,H₃BTC?terephthalic acid?as an organic ligand.A new composite Hg-IIP with higher specificity,sensitivity and stability has been successfully prepared via a surface imprinting technique,with MOF-199 as the support carrier,cysteine and MAA?methacrylic acid?as the functional ligand and functional monomer,and Hg???as the target ion.The morphology and structure of Hg-IIP was characterized by fourier transform infrared?FT-IR?and scanning electron microscopy?SEM?,which is correspond to each other.The optimum conditions to Hg-IIP for Hg???at temperature50?,time 35min and p H 6.0.The adsorption kinetics of Hg-IIP on Hg???reaches the equilibrium state in about 55min.The maximum adsorption capacity of Hg-IIP and Hg-NIP for Hg???is 84.9 and 41.97 mg/g,respectively.The adsorption process fits well with the Langmuir adsorption isothermal model,which indicates the active adsorption is single-layer adsorption.Compared to other competitive ions,Hg-IIP has specific selectivity for Hg???.In addition,the adsorption capacity to Hg???was 85.8%up to adsorption-desorption cycles,which suggests an excellent stability and reusability of Hg-IIP.