Optimization Of Functional Monomer Of Molecularly Imprinted Polymer On Carbon Microsphere Surface For Adsorbing Dibenzothiophene

Molecularly imprinted polymer (MIP) for dibenzothiophene (DBT) on the surface of carbon microspheres (CMSs) is a new kind material for selectively adsorptive of fuel, which is very important for deep or ultra-deep desulfurization of oils. In this paper, the most matching functional monomer with template DBT was selected among methacrylic acid (MAA),2-acrylamide-2-methyl sulfuric acid (AMPS) and2-vinyl pyridine (2-VP) by UV-visible spectroscopy, theory calculation and static adsorption experiments to form the stable complex with DBT for preparing MIP with good ability of selective adsorption. The results are as follows:1. The influence of different concentration of functional monomers including2-VP, MAA and AMPS on UV-visible absorption spectra of DBT molecule were investgated by UV-visible spectroscopy. The results indicated that there was an interaction between DBT and2-VP. And the optimized monomer was2-VP. Although UV-visible spectroscopy is a rapid and easy method, it is difficult to reflect the complicated system of MIP. So the results of UV-visible spectroscopy are different from the results of adsorption experiment. 2. Theoretical calculations were conducted to provide insights into the interaction between DBT and different monomers in molecular level. The structures of DBT, functional monomers and the complexes were optimized by density functional theory (DFT) at B3LYP/6-311++G(d,p) level and the interaction between them were investgated. The results indicated that according to the principle of minimum binding energy, the binding energy between DBT and MAA was calculated as-14.794691kJ/mol and the binding ability of MAA towards DBT is stronger than other two functional monomers of2-VP and AMPS. So the stable complex of MAA and DBT can be formed and MAA was selected as the optimum monomer. At the same time, theoretical vibration frequencies and the charge distribution of natural bonding orbital (NBO) theory of DBT and MAA before and after complexing was investgated. It revealed the hydrogen bond interaction enhances the binding ability of DBT and MAA except for the electrostatic interaction. The theoretical results are same with the adsorption results. Therefore, theoretical calculations are helpful for selecting optimized functional monomer of MIP system with DBT as template.3. The adsorption properties of P(2-VP)-MIP/CMSs, PMAA-MIP/CMSs and PAMPS-MIP/CMSs were investgated by the static adsorption experiments, respectively. The kinetic adsorption results for PMAA-MIP/CMSs indicate that the equilibrium time was240min and saturation adsorption amount was42.04mg/g. The relative selectivity coefficient k’ was1.97. Both adsorption ability and selective ability of PMAA-MIP/CMSs were better than other MIP. DBT molecule can be effectively removed from oil by imprinting polymer PMAA-MIP/CMSs. MAA is the optimized functional monomer for DBT.In conclusion, the hydrogen bond interaction between DBT and MAA make the complex of DBT and MAA stable binding in pre-polymerization. As-prepared PMAA-MIP/CMSs had good adsorption ability towards DBT. MAA could be used as the optimized functional monomer for preparing and exploring a kind of MIP with good recognition towards DBT.