Enhanced photocatalytic activity of molecular imprinted nano α-Fe2O3 by hydrothermal synthesis using methylene blue as structure-directing agent

Molecularly imprinted nano α-Fe2O3 samples were prepared by hydrothermal synthesis using methylene blue as a structure-directing agent. The morphology, microstructure, surface complexation parameters, and surface bonding characteristics of the samples were characterized by XRD, TEM, BET, FTIR, and surface acid-base titration. The results indicates that the adsorption on the molecularly imprinted α-Fe2O3 followed a pseudo 2nd order kinetics, and its adsorption at equilibrium rises by 22% at pH = 7. Moreover, the adsorption of methylene blue on α-Fe2O3 was consistent with that of Freundlich isotherm model. Comparative investigation was also carried out to molecularly imprinted nano α-Fe2O3 between methylene blue and p-nitropbenol. Study of XPS revealed that the adsorption between α-Fe2O3 and methylene blue was thought to be a complexation adsorption. Photocatalytic results indicates that the α-Fe2O3 showed 168% (1.68 fold) and 45.8% enhancement in photocatalytic activities toward methylene blue and p-nitrophenol, respectively. Therefore, the nano α-Fe2O3 herein demonstrates strong characteristics of molecular imprinting.