Enhanced photocatalytic New Coccine degradation and Pb(II) reduction over graphene oxide-TiO2 composite in the presence of aspartic acid-β-cyclodextrin

In this work, aspartic acid-beta-cyclodextrin (ACD) was synthesized by the reaction of beta-cyclodextrin with aspartic acid and epichlorohydrin, and graphene oxide-TiO2 (GO-TiO2) composite catalyst was prepared by a hydrothermal method. The complexation of ACD with New Coccine (NC) and Pb2+ was characterized with FT-IR and XPS, respectively, the results show that ACD can simultaneously complex NC and Pb2+. XRD analysis and SEM images of GO-TiO2 show that TiO2 platelets are well distributed on both sides of the graphene oxide sheets, and display a similar XRD pattern to the pure TiO2 nanoparticles with the typical diffraction peak of anatase phase. The effects of ACD on the photocatalytic degradation of NC and photocatalytic reduction of Pb2+ were investigated in the single pollution system, and the synergistic effects on the simultaneous photocatalytic NC degradation and Pb2+ reduction in the presence of ACD were also evaluated. The results showed that the presence of ACD was favorable to the acceleration of photocatalytic oxidation of NC and photocatalytic reduction of Pb2+ in the single pollution system, and the photocatalytic reaction rate constants of NC and Pb2+ in the presence of ACD increased 58% and 42%, respectively. For the combined pollution system, the synergistic effects on the simultaneous conversion of NC and Pb2+ in aqueous solutions were also further enhanced. ACD enhanced photocatalytic activity was attributed to the improvement of the electron transfer and mass transfer at the GO-TiO2 interface. (C) 2018 Elsevier Ltd. All rights reserved.