Application of Ion Imprinted Covalent Organic Framework in the Adsorption of Rhenium as a Substitute for Technetium

KeyWord:rhenium  covalent organic framework  ion-imprinting  technetium  radioactive

Abstract:

      Technetium£­99 has ¦Â-radioactivity and a relatively long half-life£®With perrhenate as the non-radioactive structural substitute for pertechnetate£¬an ion imprinted covalent organic frameworks£¨IICOFs£© were prepared in this paper£®Owing to the high specific surface area of COF and the selectivity of ion imprinting technology£¬the prepared IICOFs were applied successfully to the rapid adsorption and extraction of perrhenate anions in real water samples£®Firstly£¬the vinyl functionalized COF£­V was obtained£¬based on the reaction between 1£¬4-dialdehyde-2£¬5-divinylbenzene£¨Dva£© and 1£¬3£¬5-tris£¨4-aminophenyl£©benzene£¨Tab£© under the microwave assistance. And then£¬with N-vinylimidazole£¨VI£© and 4-chloromethylstyrene£¨4-VBC£© as the functional monomers£¬the positively charged binding sites were achieved on the COF£­V£®Finally£¬the IICOFs were synthesized through the electrostatic action and radical polymerization£®Meanwhile£¬effects of pH value£¬adsorption time£¬temperature£¬adsorption dose and initial concentration on the adsorption performance of the IICOFs were investigated£¬and the specific recognition of IICOFs was explored through interference experiments£®The adsorption equilibrium could be achieved within 2 min£®The study of adsorption thermodynamics showed that the adsorption for perrhenate anions was a spontaneous exothermic process£¬following a pseudo-second order model in kinetics£®At 298.15 K£¬the maximum adsorption capacity was calculated to be 416.67 mg/g according to the Langmuir model£®Compared with the non imprinted composites£¬IICOFs exhibited a higher selectivity£¬a faster kinetics and a larger adsorption capacity£®For the Pearl River water and the tailings leachate water samples that were spiked with perrhenate anion of 2.0 ¡Á 10£­4 mol/L£¬the adsorption efficiencies reached 87% and 98%£¬respectively£¬indicating that the IICOFs could be used for the effective removal of perrhenate anion in real environment£®This technique provides a new way for the effective adsorption£¬separation and extraction of pertechnetate£¬as well as the recycle of pertechnetate resource from environments£®