Synthesis of Ag3PO4 immobilized with sepiolite and its photocatalytic performance for 2,4-dichlorophenol degradation under visible light irradiation

A novel Ag3PO4-sepiolite composite photocatalyst was first synthesized using the liquid deposition method. And its characteristics were measured by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface, UV-vis diffuse spectra and photoluminescence (PL). Moreover, the photocatalytic performance of Ag3PO4-sepiolite was tested for 2,4-DCP degradation under visible light irradiation, and enhanced photocatalytic activity and stability were achieved. Besides, the response surface methodology based on Box-Behnken design (BBD) was employed to investigate the effects of different reaction conditions on the removal of 2,4-DCP. The optimum conditions for 2,4-DCP degradation were as follows: solution pH value of 4.01, H2O2 concentration of 35.24 mM and catalyst dosage of 0.36 g L-1. Under these conditions, the experimental values for 2,4-DCP and TOC removal efficiencies were of 84.50% and 64.39%, which consisted with the predicted values of 84.65% and 64.48%, respectively. Furthermore, the free radical capture experiments indicated that reactive species of OH center dot, O-2(center dot-) and h(+) were the main participants for oxidizing 2,4-DCP. The reaction intermediates were also identified by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometer (GC-MS) technique. (C) 2015 Elsevier B.V. All rights reserved.