Synthesis of Ag-NPs decorated SnO2 for enhanced photocatalytic degradation of Eosin B based on central composite design

Abstract

The photocatalytic degradation performance of Eosin B using synthesized pure and silver nanoparticles (xAg-NPs) decorated tin dioxide (SnO₂) were investigated. The synthesized nanoparticles were characterized using UV–Vis spectrophotometer, XRD, TEM, FESEM, EDS, and elemental mapping. XRD analysis confirmed that both SnO₂ and Ag-SnO₂ nanoparticles possess crystalline structures, with average sizes of 15 and 13 nm, respectively. TEM images revealed that the tetragonal morphology of SnO₂ nanoparticles changed to spherical with Ag-NPs decoration. Furthermore, the band-gap of the particles decreased from 3.6 to 3.4 eV after decoration with Ag-NPs to SnO₂. The photocatalytic process was evaluated using response surface methodology (RSM) based on central-composite design (CCD), considering four independent factors. Various operational variables, such as initial dye concentration (10–30 mg/l), pH (4–10), catalyst amount (40–200 mg), and irradiation time (60–240 min), were considered to identify the optimal conditions for the photodegradation of Eosin B. Analysis of variance (ANOVA) was applied to detect the influential factors and their significance levels. Process optimization revealed that the highest photocatalytic degradation efficiency of 100 % was obtained at an irradiation time, pH, catalyst amount, and dye concentration of 239.8 min, 6.74, 185.6 mg, and 10.0 mg/l, respectively. The degradation reactions corresponded well with first-order kinetics.