Silver-ruthenium bimetallic nanoparticles as sacrificial heterogeneous persulfate activator in situ chemical oxidation of dye

Abstract

Silver-ruthenium bimetallic (Ag-Ru) synthesized using green chemical co-reduction method. The valence state, composition, crystallinity, shape, and size of Ag-Ru were evaluated by using XPS, EDX, XRD, SEM, and TEM measurements. The XPS analysis indicates that charge transfer takes place contacting silver and ruthenium moieties. To present the advantages of Ag-Ru NPs as heterogeneous activator, sulfate radical based advanced oxidation processes for patent blue V dye degradation was chosen as a model contaminant. The Ag-Ru/S2O82− system shows great catalytic activity at lower dye concentration, pH, increasing the dosage of NPs, and persulfate. The activated system showed a much higher dye oxidation rate compared to either Ag-Ru or S2O82− alone. The degradation percentage decreases with increasing the dye concentration as well as pH of the reaction media. The persulfate exhibits complex kinetic behavior on the degradation of dye. The activation energy for the system was 57.7 kJ/mol calculated from Arrhenius equation. The oxidation of dye follows pseudo-first order kinetics (kapp = 0.029 min−1). The excellent activation performance of Ag-Ru might be due to the synergistic effect of silver and ruthenium. The reaction mechanism of Ag-Ru bimetallic activation of persulfate was elucidated and discussed. The electron transfer from Ru3+ / Ru2+ and Ag2+/Ag+ plays significant role in the regeneration of active radicals. In addition, Ag-Ru was under goes complete oxidative dissolution with persulfate.