Boosted photocatalytic effect of binary AgI/Ag2WO4 nanocatalyst: characterization and kinetics study towards ceftriaxone photodegradation.

Abstract

In modern chemistry, great interest has been paid to introducing outstanding photocatalysts for degrading organic pollutants. Herein, a highly efficient binary AgI/Ag2WO4 photocatalyst was prepared from AgI and Ag2WO4 nanoparticles (NPs) and characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), and Fourier transform infrared (FT-IR) techniques. In the Scherrer model, the average crystallite sizes of 34.9, 42.0, and 24.1nm were estimated for the AgI, Ag2WO4, and the binary catalyst, while the values were 91, 13, and 85nm by the Williamson-Hall model. FTIR confirmed the presence of W-O-W, O-W-O, Ag-I, and O-Ag-O bonds in the coupled material. DRS results showed absorption edge wavelengths of 451, 462, and 495nm (corresponding to the band gap values of 2.75, 2.68, and 2.51eV) for Ag2WO4, AgI, and AgI/Ag2WO4 catalyst, respectively. Synergistic photocatalytic activity of the coupled system was achieved towards ceftriaxone (CTX) in an aqueous solution (about 33% 10ppm CTX solution was degraded without any optimization in the initial conditions of catal dose 0.3g/L (Ag2WO4:AgI with mole ratio 1:2 and 30min abrasion time), and irrad. time 45min, CCTX). This boosted effect depended on the AgI:Ag2WO4 mole ratio and grinding time for the mechanical preparation of the binary catalyst (optimums: mole ratio of 4:1 and time 30min). The photodegradation kinetics obeyed the Hinshelwood model with the apparent first-order rate constant (k) of 0.013min-1 (t1/2 = 53.30min). Performing the COD on the photodegraded CTX solutions got a Hinshelwood plot with a slope of 0.019min-1 (t1/2 = 36.5min).