Molecularly-imprinted Material for Dibenzothiophene Recognition Prepared by Surface Imprinting Methods

Molecular imprinting has been conducted on the surface of TiO2 particles to enable the recognition of dibenzothiophene (DBT) molecules. This was achieved via the use of a novel surface molecular-imprinting technique. The adsorption behaviour of the dibenzothiophene-imprinted material (D-MIP/TiO2) was evaluated using batch adsorption experiments to determine the kinetic, isotherm and thermodynamic parameters. The experimental results showed that the adsorption process followed pseudo-second-order kinetics and that the experimental data were well fitted by the Freundlich adsorption equation. This indicated that adsorption involved a multilayer process. Values of the Gibbs' free energy (Delta G(0)) ranged from -7.11 kJ/mol to -9.36 kJ/mol over the temperature interval 298-318 K, indicating that the adsorption was endothermic in nature. In addition, D-MIP exhibited selective recognition of DBT relative to other similar compounds such as benzothiophene (BT), 4-methyldibenzothiphene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). In the corresponding selectivity test, D-MIP/TiO2 showed a greater adsorption capacity towards DBT than BT, 4-MDBT and 4,6-DMDBT. The large imprinting factor (ca. 2.5) exhibited by D-MIP/TiO2 for DBT could be explained in terms of a covalent assembly mechanism.