Excellent performance of ordered Ag-g-C3N4/SBA-15 for photocatalytic ozonation of oxalic acid under simulated solar light irradiation

Ordered Ag-g-C3N4/SBA-15 was successfully synthesized using SBA-15 as a template and support. The samples were characterized by TEM, XRD, XPS, N-2 adsorption-desorption. The results showed that metallic silvers with diameter 15 nm were distributed on the surface of g-C3N4 thin-layered. The specific surface area of the composite was 563.4 m(2)g(-1). As the final products for ozonation, oxalic acid was used to investigate its catalytic ability in heterogeneous photocatalytic ozonation under simulated solar light irradiation. Ordered Ag-g-C3N4/SBA-15 with the mass ratio of silver nitrate/dicyandiamide around 4% was found to be the most efficient for oxalic acid degradation. The kinetic constant was 1.60 and 2.52 times as high as that of solar light/Ag-g-C3N4/O-3 and solar light/g-C3N4/O-3 process, respectively. It demonstrated that both the Ag nanoparticles and improved specific surface area contributed to the enhancement, which promoted the decomposition of O-3 and increased the active sites in reaction. The synergy index for photocatalytic ozonation of oxalic acid was calculated to be 5.71, which indicated a superior synergistic effect between photocatalysis and ozonation. In addition, 4% Ag-g-C3N4/SBA-15 samples showed good stability in photocatalytic ozonation process by cycled for four times, and the mechanism was also confirmed in this study. It is suggested that Ag-g-C3N4/SBA-15 composites is a promising catalyst for the practical application of photocatalytic ozonation. (C) 2017 Elsevier B.V. All rights reserved.