Comparative studies of synthesis of Ag/Ag2O nanoparticles by sol–gel and sonochemical method as removal of Cr(VI)

Ag/Ag2O nanocomposites have been successfully synthesized by sol–gel and sonochemical methods. Ag/Ag2O from the sol–gel method produced more silver amount (9.5%) than the sonochemical method (0.9%). In contrast, the sonochemical method has a larger specific surface area and a smaller particle size with an average particle size of 68.9 nm. SEM studies showed that Ag/Ag2O from both methods had agglomerated homogeneous spherical shapes. UV–vis spectroscopy analysis showed Ag/Ag2O sol–gel method has a smaller band gap of up to 1.29 eV. For Cr(VI) adsorption equilibrium data, the key parameters such as kinetics, equilibrium, and thermodynamics, were compared. For the adsorption and photocatalytic process, the Ag/Ag2O synthesized from the sonochemical method showed more satisfactory results. The Cr(VI) removal results for adsorption and photocatalysis for Ag/Ag2O sonochemical methods were 74.30 and 94.80%, respectively in 90 min. The reaction mechanism involves Ag as a metal which acts as an electron scavenger to reduce recombination.