The synthesis and characterization of Ag/Ag2O/TiO2/NGP composites as adsorbents and photocatalysts for wastewater removal

Abstract

An Ag/Ag2O/TiO2/NGP with different nanographene platelets (NGP) weight percents was synthesized using the hydrothermal method. The NGP weight percent was 5, 10, and 15 weight percent, respectively. The structural properties of the samples were characterized by X-ray diffraction. The optical properties of the samples were investigated by UV-Vis spectroscopy and their thermal properties were investigated by Thermo Gravimetric Analysis and Differential Thermal Analysis. The existence of a cubic structure from Ag and Ag2O, an anatase from TiO2, and a graphitic like structure from NGP indicated that the samples were successfully formed. The maximum light absorption at 435 nm indicated the existence of surface plasmon resonance (SPR) from silver nanoparticles. The phase transformation of Ag2O to Ag occurred at 435 °C. Adsorption and the photocatalytic performance were investigated in the degradation of methylene blue from the aqueous solution. The adsorption ability of Ag/Ag2O/TiO2/NGP composites increased by increasing the NGP weight percent. The adsorption process of MB followed pseudo-second-order kinetic reactions. The photocatalytic activity of Ag/Ag2O/TiO2/NGP showed that Ag/Ag2O/TiO2/NGP with a 10 weight percent NGP exhibited the highest photocatalytic performance, with a removal ability of approximately 96 percent.