Applied Catalysis B: Environmental, Vol.212, 185-192, 2017
Efficient enantioselective degradation of the inactive (S)-herbicide dichlorprop on chiral molecular-imprinted TiO2
The chiral compound 2-(2,4-dichlorophenoxy) propionic acid (DCPP) is a widely used herbicide; the active (R)-DCPP enantiomer has been reported to often be preferentially degraded, whereas the inactive (S)-DCPP with greater toxicity remains in the environment. In this study, we achieved efficient enantioselective recognition and controllable degradation of (S)-DCPP on a photoelectrocatalytic (PEC) surface by introducing a molecular imprinting technique. We fabricated an (S)-DCPP-molecular-imprinted single-crystalline TiO2 (S-TiO2 (SC)) photoelectrode in situ by constructing (S)-DCPP molecular imprinting sites on the surface of 1D single-crystalline TiO2 nanorods. The results revealed that the S-TiO2 (SC) exhibited higher PEC oxidation activity (0.500 mA/cm(2)) and electrochemical surface adsorption (4.37 x 10-12 mol cm-2 mg) against the target (S)-DCPP than against the non-target (R)-DCPP. Additionally, the S-TiO2 (SC) achieved excellent enantioselective PEC degradation of (S)-DCPP in both the single component and racemic systems. The k value of (S)-DCPP was 0.156 h(-1) after 6 h, which was 2.6 times greater of (R)-DCPP (0.060 h(-1)). Finally, when (S)-DCPP was present with 100-fold concentration of (R)DCPP and five other contaminants, a greater anti-interference ability was demonstrated by S-TiO2 (SC). This study highlights the need for further investigations on the enantioselective degradation of a specific enantiomer in chiral enantiomers. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Herbicide dichlorprop;(S)-DCPP enantiomers;Enantioselective degradation;Molecular-imprinted single-crystalline TiO2;Anti-interference ability