Three-dimensional electrochemical activation of peroxydisulfate using AgNP/rGO hydrogel for efficient acid orange 74 degradation

Three-dimensional (3D) electrochemical systems effectively improve electron transfer rates by increasing electrode surface area and active site density using particle microelectrodes. To investigate the potential utility of a transition metal–carbon particle electrode, a 3D electrochemical activation system for peroxydisulfate (PDS) using a silver nanoparticle (AgNP)–incorporated reduced graphene oxide (rGO) hydrogel particle electrode (3D-PDS/AgNP/rGO) was constructed for achieving enhanced acid orange 74 (AO 74) degradation. The AgNP/rGO hydrogel was prepared via a low-temperature hydrothermal reduction method in which AgNPs were uniformly dispersed within the porous rGO matrix. Optimization of the 3D-PDS/AgNP/rGO process parameters demonstrated that AO 74 degradation efficiency was strongly dependent on AgNP/rGO concentration, PDS concentration, applied current, and solution pH. The degradation efficiency reached 96.31% within 3 h, and the degradation rate constant exhibited a 2.35-fold higher than that of a 2D-PDS system that lacked a particle electrode. Water matrix analysis revealed that Cl − enhanced AO 74 degradation, whereas CO 3 2− and PO 4 3− inhibited it. The use of radical scavengers identified hydroxyl radicals and sulfate radicals as the generated dominant reactive species. 3D-PDS/AgNP/rGO exhibited remarkable stability, maintaining 84.44% degradation efficiency after five cycles and outperforming the conventional 2D-PDS system. This study demonstrated that 3D-PDS/AgNP/rGO met the technical requirements for efficient degradation of organic pollutants and exhibited application potential in azo dye wastewater treatment. • Synthesis of AgNP incorporated rGO hydrogel particle electrode • 3D-PDS/AgNP/rGO system for efficient degradation of AO 74 solution • OH dominates the degradation of AO 74 • Stability of rGO structure and controlled Ag dissolution maintain high reusability