Structural Refinement, Morphological Features, Optical Properties, and Adsorption Capacity of alpha-Ag2WO4 Nanocrystals/SBA-15 Mesoporous on Rhodamine B Dye

Abstract

alpha-Ag2WO4 nanocrystals, mesoporous silica (SBA-15), and alpha-Ag2WO4/SBA-15 as a nanocomposite were prepared by sonochemical, hydrothermal, and in situ sonochemical methods respectively. Samples were characterized by X-ray diffraction (XRD), Rietveld refinement, micro-Raman, Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), N-2 adsorption/desorption, ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy, and Zeta potential. XRD patterns, Rietveld refinement, and XPS spectra confirmed the formation of alpha-Ag2WO4, SBA-15, and alpha-Ag2WO4/SBA-15. XPS spectra evidenced the formation of metallic silver during analysis. FE-SEM images illustrated the deposition of alpha-Ag2WO4 nanocrystals mainly on the external surface of SBA-15. N-2 adsorption data showed that the textural properties of alpha-Ag2WO4/SBA-15 were similar to pure SBA-15. Zeta potential data demonstrated that all samples synthetized have negatively charged surface. The materials were tested as adsorbents for the dye cationic rhodamine B. The adsorption behavior of rhodamine B onto alpha-Ag2WO4, SBA-15, and alpha-Ag2WO4/SBA-15 correspond to Langmuir adsorption isotherm and pseudo-second-order kinetics. The maximum adsorption capacity of alpha-Ag2WO4/SBA-15 was up to 150 mg g(-1) and 99% removal efficiency for RhB 20 mg L-1 in 15 min. Furthermore, 80% of RhB could be recuperated from adsorbents at pH 7. Graphic