Synthesis of Ag/ZnO-AC composite photocatalyst: spectroscopic investigation, parameter optimization, synergistic effect and performance enhancement for cost-effective photocatalytic degradation of phenols and dyes.

A ternary photocatalyst composite-Silver decorated on ZnO supported with activated carbon (Ag/ZnO-AC) was investigated for the synthesis, characterization and UV assisted photocatalytic degradation of phenols and dyes present in wastewater. XPS and TEM revealed the elemental composition and formation of ternary Ag/ZnO-AC composite. Different operational parameters including the effect of calcination temperature, catalyst dose, initial concentration of pollutant and the effect of H2O2 and ethanol were studied. The photocatalytic activity was assessed for the degradation of p-Nitrophenol (PNP), o-Nitrophenol (ONP), and dye methyl orange (MO) under UV irradiation by ZnO, Ag/ZnO and Ag/ZnO-AC catalyst. The degradation for PNP, ONP and MO in presence of UV light were found to be in the order Ag/ZnO-AC>Ag/ZnO>ZnO. Improved degradation by Ag/ZnO-AC is attributed to high charge separation and greater adsorption of pollutant because of the combination of Ag and AC leading to a synergistic effect in the catalyst. Along with the high reusability, the composite catalyst Ag/ZnO-AC was found to be non-selective and cost-effective for the degradation of phenols as well as dyes. The as synthesized ternary composite Ag/ZnO-AC can be efficiently used as a photocatalyst for the degradation of recalcitrant and other deleterious contaminants present in wastewater.